Time to the minute
By the end of this chapter you will be able to
- Read the time on an analogue clock to the minute
- Write a time on a 12-hour and a 24-hour clock
- Convert between hours and minutes
- Know the facts about minutes, hours and days
- Find the time between two times
You should already know
- Telling the time to the hour and half hour (Level 3, chapter 9)
- Times tables and division (chapters 4 to 6)
Where this leads
- Solving problems with the four operations (chapter 9)
Step-by-step practice: maths (Level 4). Small steps, repeated until fluent. Content: Tell and write the time from an analogue clock to the minute, and read 12-hour and 24-hour clocks (M4), Estimate and read time with increasing accuracy to the nearest minute; record and compare time in hours and minutes (M5), Know the number of minutes in an hour, hours in a day and days in each month (M6), Compare and find durations, for example how long from 14:20 to 15:05 (M7).
Exercise P Do you remember?
Non-calculatorMethod. Count in nines twice, or double 9.
- Double 9. Two groups of 9.9 + 9
- Add them. Nine and nine make eighteen.9 + 9 = 18
- Write the answer. This is the total.18
Check. Check: 18 ÷ 2 = 9.
Watch out. Doubling is multiplying by 2.
Method. Count in fives until you reach 25.
- Count in fives. Each count is one group of 5.5, 10, 15, 20, 25
- Count the groups. Count how many numbers you said.5 groups
- Write the answer. This is the number of groups.5
Check. Check: 5 × 5 = 25.
Watch out. Count the groups, not the total.
Method. Subtract 10 three times.
- Start at 530. It is where we begin.530
- Take away 10 each time. Each count takes away 10.530 - 10 = 520, then 510, then 500
- Write the answer. This is the last number we reached.500
Check. Check: 500 + 30 = 530.
Watch out. Only the tens digit changes when you count in tens.
Method. Look at the tens and ones.
- Look at the tens and ones. 86 is more than 50.86 is 50 or more
- Round up to the next hundred. The hundreds become 4.300 rounds up to 400
- Write the answer. This is the nearest hundred.400
Check. Check: 400 is 14 away from 386, and 300 is 86 away.
Watch out. Fifty or more rounds up.
Method. Multiply, then add zero.
- Multiply 3 by 7. Three groups of 7.3 × 7 = 21
- Add zero. Adding zero does not change the answer.21 + 0 = 21
- Write the answer. This is the total.21
Check. Check: 21 ÷ 3 = 7.
Watch out. Adding zero never changes a number.
Reading an analogue clock to the minute
The short hand shows the hour. The long hand shows the minutes. Each number on the clock face is 5 minutes, and each small mark is 1 minute.
Read the minutes first, from the long hand. Then read the hour from the short hand.
Key ideas
- The long hand shows the minutes.
- Each number is 5 minutes; count the small marks for each extra minute.
- Write the minutes with two digits, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.4 fives = 20 minutes
- Read the hour hand, the short hand. It has passed the 7, so the hour is 7.the hour is 7
- Write the time. Write the hour, then a colon, then two digits for the minutes.7:20
Check. Check: 7 o'clock is the hour, and 20 minutes past it.
Watch out. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. It points to the 9, which is 45 minutes.9 fives = 45 minutes
- Read the hour hand, the short hand. The hour hand is just before the 3, so the hour is 2.the hour is 2
- Write the time. Quarter to three is 2:45.2:45
Check. Check: 2:45 is 15 minutes before 3:00.
Watch out. The long hand near 9 means 45 minutes past the hour.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. It is past the 1, which is 5 minutes, and 3 small marks further on.5 + 3 = 8 minutes
- Read the hour hand, the short hand. It has passed the 11, so the hour is 11.the hour is 11
- Write the time. Write two digits for the minutes.11:08
Check. Check: 11:08 is 8 minutes past 11.
Watch out. Count each small mark as 1 minute.
Watch out
Watch out. The short hand does not give the minutes. A time of 2:45 has the long hand at the 9, not the 2.
Exam tip
Grown-up tip. Ask: “Where is the long hand? How many minutes is that?” Then ask: “Where is the short hand?”
Exercise 8A Practice: reading an analogue clock
Non-calculatorMethod. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.8 fives = 40 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 12
- Write the time. Write the hour, then a colon, then two digits for the minutes.12:40
Check. Check: the hour is 12, and the long hand shows 40 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.0 fives = 0 minutes
- Count the small marks past that number. Each small mark is 1 minute.0 + 4 = 4 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 9
- Write the time. Write the hour, then a colon, then two digits for the minutes.9:04
Check. Check: the hour is 9, and the long hand shows 4 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.8 fives = 40 minutes
- Count the small marks past that number. Each small mark is 1 minute.40 + 3 = 43 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 9
- Write the time. Write the hour, then a colon, then two digits for the minutes.9:43
Check. Check: the hour is 9, and the long hand shows 43 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.11 fives = 55 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 7
- Write the time. Write the hour, then a colon, then two digits for the minutes.7:55
Check. Check: the hour is 7, and the long hand shows 55 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.0 fives = 0 minutes
- Count the small marks past that number. Each small mark is 1 minute.0 + 3 = 3 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 6
- Write the time. Write the hour, then a colon, then two digits for the minutes.6:03
Check. Check: the hour is 6, and the long hand shows 3 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.8 fives = 40 minutes
- Count the small marks past that number. Each small mark is 1 minute.40 + 3 = 43 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 2
- Write the time. Write the hour, then a colon, then two digits for the minutes.2:43
Check. Check: the hour is 2, and the long hand shows 43 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.10 fives = 50 minutes
- Count the small marks past that number. Each small mark is 1 minute.50 + 2 = 52 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 4
- Write the time. Write the hour, then a colon, then two digits for the minutes.4:52
Check. Check: the hour is 4, and the long hand shows 52 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.4 fives = 20 minutes
- Count the small marks past that number. Each small mark is 1 minute.20 + 1 = 21 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 3
- Write the time. Write the hour, then a colon, then two digits for the minutes.3:21
Check. Check: the hour is 3, and the long hand shows 21 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.1 fives = 5 minutes
- Count the small marks past that number. Each small mark is 1 minute.5 + 3 = 8 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 7
- Write the time. Write the hour, then a colon, then two digits for the minutes.7:08
Check. Check: the hour is 7, and the long hand shows 8 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.0 fives = 0 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 7
- Write the time. Write the hour, then a colon, then two digits for the minutes.7:00
Check. Check: the hour is 7, and the long hand shows 0 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.9 fives = 45 minutes
- Count the small marks past that number. Each small mark is 1 minute.45 + 3 = 48 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 11
- Write the time. Write the hour, then a colon, then two digits for the minutes.11:48
Check. Check: the hour is 11, and the long hand shows 48 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.3 fives = 15 minutes
- Count the small marks past that number. Each small mark is 1 minute.15 + 4 = 19 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 1
- Write the time. Write the hour, then a colon, then two digits for the minutes.1:19
Check. Check: the hour is 1, and the long hand shows 19 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.2 fives = 10 minutes
- Count the small marks past that number. Each small mark is 1 minute.10 + 3 = 13 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 4
- Write the time. Write the hour, then a colon, then two digits for the minutes.4:13
Check. Check: the hour is 4, and the long hand shows 13 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.8 fives = 40 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 5
- Write the time. Write the hour, then a colon, then two digits for the minutes.5:40
Check. Check: the hour is 5, and the long hand shows 40 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.3 fives = 15 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 3
- Write the time. Write the hour, then a colon, then two digits for the minutes.3:15
Check. Check: the hour is 3, and the long hand shows 15 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.6 fives = 30 minutes
- Count the small marks past that number. Each small mark is 1 minute.30 + 4 = 34 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 9
- Write the time. Write the hour, then a colon, then two digits for the minutes.9:34
Check. Check: the hour is 9, and the long hand shows 34 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
The 12-hour and 24-hour clock
A 12-hour clock uses a.m. (the morning) and p.m. (the afternoon and evening). A 24-hour clock counts from 00:00 to 23:59.
For p.m. times, add 12 to the hour, unless the hour is 12. Midnight is 00:00.
Key ideas
- a.m. is the morning; p.m. is after 12 noon.
- On a 24-hour clock, add 12 to the hour for p.m. times.
- The minutes stay the same.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. p.m. is after 12 noon.p.m.
- Change the hour. For p.m. times, add 12 to the hour.3 + 12 = 15
- Write the time. Keep two digits for the hour and minutes.15:45
Check. Check: 15:45 is 3:45 in the afternoon.
Watch out. 12:30 p.m. is 12:30, not 00:30.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Find the hour on a 12-hour clock. Subtract 12 from the hour if it is after 12.20 - 12 = 8
- Decide a.m. or p.m. Times from 12:00 onwards are p.m.p.m.
- Write the time. Write the hour, the minutes, then p.m.8:30 p.m.
Check. Check: 8:30 p.m. is 20:30 on a 24-hour clock.
Watch out. The minutes never change.
Method. A 24-hour clock counts from 00:00 to 23:59. For a.m. times, keep the hour.
- Note the time of day. a.m. is the morning.a.m.
- Change the hour. For a.m. times, the hour stays the same.8 stays 8, shown as 08
- Write the time. Use two digits for the hour.08:10
Check. Check: 08:10 is 8:10 in the morning.
Watch out. Midnight is 00:00.
Watch out
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Only the hours before 12 get 12 added.
Exam tip
Grown-up tip. Ask: “Is it morning or afternoon? Add 12 for an afternoon time.”
Exercise 8B Practice: 12-hour and 24-hour times
Non-calculatorMethod. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.a.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.1 stays the same
- Write the time. Keep two digits for the hour and minutes.01:19
Check. Check: 01:19 is 1:19 a.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.a.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.2 stays the same
- Write the time. Keep two digits for the hour and minutes.02:20
Check. Check: 02:20 is 2:20 a.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.a.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.3 stays the same
- Write the time. Keep two digits for the hour and minutes.03:25
Check. Check: 03:25 is 3:25 a.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.p.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.12 stays the same
- Write the time. Keep two digits for the hour and minutes.12:41
Check. Check: 12:41 is 12:41 p.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Note the time of day. a.m. is the morning. p.m. is the afternoon.a.m.
- Change the hour. For p.m., add 12 to the hour unless it is 12. 12 a.m. is 00.8 gives 08
- Write the time. Use two digits for the hour.08:33
Check. Check: 08:33 is the same time of day as 8:33 a.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Note the time of day. a.m. is the morning. p.m. is the afternoon.a.m.
- Change the hour. For p.m., add 12 to the hour unless it is 12. 12 a.m. is 00.5 gives 05
- Write the time. Use two digits for the hour.05:57
Check. Check: 05:57 is the same time of day as 5:57 a.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.p.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.2 + 12
- Write the time. Keep two digits for the hour and minutes.14:16
Check. Check: 14:16 is 2:16 p.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Find the hour on a 12-hour clock. Subtract 12 from the hour if it is after 12. Midnight and noon are 12.08 is 8 on a 12-hour clock
- Decide a.m. or p.m. Times before 12:00 are a.m. and times from 12:00 are p.m.a.m.
- Write the time. Write the hour, the minutes, then a.m. or p.m.8:20 a.m.
Check. Check: 8:20 a.m. is the same time of day as 8:20 a.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.p.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.9 + 12
- Write the time. Keep two digits for the hour and minutes.21:59
Check. Check: 21:59 is 9:59 p.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.a.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.9 stays the same
- Write the time. Keep two digits for the hour and minutes.09:23
Check. Check: 09:23 is 9:23 a.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Note the time of day. a.m. is the morning. p.m. is the afternoon.a.m.
- Change the hour. For p.m., add 12 to the hour unless it is 12. 12 a.m. is 00.4 gives 04
- Write the time. Use two digits for the hour.04:24
Check. Check: 04:24 is the same time of day as 4:24 a.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.a.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.6 stays the same
- Write the time. Keep two digits for the hour and minutes.06:56
Check. Check: 06:56 is 6:56 a.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Note the time of day. a.m. is the morning. p.m. is the afternoon.a.m.
- Change the hour. For p.m., add 12 to the hour unless it is 12. 12 a.m. is 00.3 gives 03
- Write the time. Use two digits for the hour.03:21
Check. Check: 03:21 is the same time of day as 3:21 a.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Note the time of day. a.m. is the morning. p.m. is the afternoon.a.m.
- Change the hour. For p.m., add 12 to the hour unless it is 12. 12 a.m. is 00.6 gives 06
- Write the time. Use two digits for the hour.06:27
Check. Check: 06:27 is the same time of day as 6:27 a.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.a.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.4 stays the same
- Write the time. Keep two digits for the hour and minutes.04:49
Check. Check: 04:49 is 4:49 a.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Note the time of day. a.m. is the morning. p.m. is the afternoon.p.m.
- Change the hour. For p.m., add 12 to the hour unless it is 12. 12 a.m. is 00.9 gives 21
- Write the time. Use two digits for the hour.21:08
Check. Check: 21:08 is the same time of day as 9:08 p.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Converting between hours and minutes
There are 60 minutes in 1 hour. To change hours to minutes, multiply by 60 and add any extra minutes.
To change minutes to hours and minutes, divide by 60. The number of whole hours is the answer, and the remainder is the minutes.
Key ideas
- 1 hour = 60 minutes.
- Hours to minutes: multiply by 60, then add the extra minutes.
- Minutes to hours: divide by 60; the remainder is the minutes.
Method. There are 60 minutes in an hour. Change the hours to minutes, then add the extra minutes.
- Change 2 hours to minutes. There are 60 minutes in 1 hour.2 × 60 = 120
- Add the minutes. Put the extra 35 minutes on the end.120 + 35 = 155
- Write the answer. This is the total number of minutes.155
Check. Check: 155 minutes is 2 hours and 35 minutes.
Watch out. Do not write 2 hours 35 minutes as 235.
Method. There are 60 minutes in an hour. Divide by 60 to find the hours, and the remainder is the minutes.
- Count how many whole hours there are. Every 60 minutes is 1 hour.190 ÷ 60 = 3 remainder 10
- Find the minutes left over. The remainder is the extra minutes.190 - 180 = 10
- Write the answer. Say the hours, then the minutes.3 hours 10 minutes
Check. Check: 3 hours is 180 minutes and 10 more is 190.
Watch out. Do not write 190 minutes as 1 hour 90 minutes.
Method. There are 60 minutes in an hour. Divide by 60 to find the hours.
- Count how many whole hours there are. Two full hours are 120 minutes.125 ÷ 60 = 2 remainder 5
- Find the minutes left over. The remainder is the extra minutes.125 - 120 = 5
- Write the answer. Say the hours, then the minutes.2 hours 5 minutes
Check. Check: 2 hours is 120 minutes and 5 more is 125.
Watch out. Check the remainder is less than 60.
Watch out
Watch out. 2 hours 35 minutes is 155 minutes, not 235 minutes. Multiply the hours by 60 first.
Exam tip
Grown-up tip. Ask the child to count in sixties: 60, 120, 180, to get the number of minutes in whole hours.
Exercise 8C Practice: hours and minutes
Non-calculatorMethod. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.229 ÷ 60 = 3 remainder 49
- Find the minutes left over. The remainder is the extra minutes.229 - 180 = 49
- Write the answer. Say the hours, then the minutes.3 hours 49 minutes
Check. Check: 3 hours is 180 minutes, and 49 more is 229.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.192 ÷ 60 = 3 remainder 12
- Find the minutes left over. The remainder is the extra minutes.192 - 180 = 12
- Write the answer. Say the hours, then the minutes.3 hours 12 minutes
Check. Check: 3 hours is 180 minutes, and 12 more is 192.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.75 ÷ 60 = 1 remainder 15
- Find the minutes left over. The remainder is the extra minutes.75 - 60 = 15
- Write the answer. Say the hours, then the minutes.1 hour 15 minutes
Check. Check: 1 hour is 60 minutes, and 15 more is 75.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Change 2 hours to minutes. There are 60 minutes in 1 hour.2 × 60 = 120
- Add the minutes. Put the extra minutes on the end.120 + 17 = 137
- Write the answer. This is the total number of minutes.137
Check. Check: 2 hours is 120 minutes, and 17 more is 137.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.169 ÷ 60 = 2 remainder 49
- Find the minutes left over. The remainder is the extra minutes.169 - 120 = 49
- Write the answer. Say the hours, then the minutes.2 hours 49 minutes
Check. Check: 2 hours is 120 minutes, and 49 more is 169.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.222 ÷ 60 = 3 remainder 42
- Find the minutes left over. The remainder is the extra minutes.222 - 180 = 42
- Write the answer. Say the hours, then the minutes.3 hours 42 minutes
Check. Check: 3 hours is 180 minutes, and 42 more is 222.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.64 ÷ 60 = 1 remainder 4
- Find the minutes left over. The remainder is the extra minutes.64 - 60 = 4
- Write the answer. Say the hours, then the minutes.1 hour 4 minutes
Check. Check: 1 hour is 60 minutes, and 4 more is 64.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.252 ÷ 60 = 4 remainder 12
- Find the minutes left over. The remainder is the extra minutes.252 - 240 = 12
- Write the answer. Say the hours, then the minutes.4 hours 12 minutes
Check. Check: 4 hours is 240 minutes, and 12 more is 252.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.111 ÷ 60 = 1 remainder 51
- Find the minutes left over. The remainder is the extra minutes.111 - 60 = 51
- Write the answer. Say the hours, then the minutes.1 hour 51 minutes
Check. Check: 1 hour is 60 minutes, and 51 more is 111.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.249 ÷ 60 = 4 remainder 9
- Find the minutes left over. The remainder is the extra minutes.249 - 240 = 9
- Write the answer. Say the hours, then the minutes.4 hours 9 minutes
Check. Check: 4 hours is 240 minutes, and 9 more is 249.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Change 3 hours to minutes. There are 60 minutes in 1 hour.3 × 60 = 180
- Add the minutes. Put the extra minutes on the end.180 + 37 = 217
- Write the answer. This is the total number of minutes.217
Check. Check: 3 hours is 180 minutes, and 37 more is 217.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Change 1 hour to minutes. There are 60 minutes in 1 hour.1 × 60 = 60
- Add the minutes. Put the extra minutes on the end.60 + 41 = 101
- Write the answer. This is the total number of minutes.101
Check. Check: 1 hour is 60 minutes, and 41 more is 101.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Change 5 hours to minutes. There are 60 minutes in 1 hour.5 × 60 = 300
- Add the minutes. Put the extra minutes on the end.300 + 29 = 329
- Write the answer. This is the total number of minutes.329
Check. Check: 5 hours is 300 minutes, and 29 more is 329.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.143 ÷ 60 = 2 remainder 23
- Find the minutes left over. The remainder is the extra minutes.143 - 120 = 23
- Write the answer. Say the hours, then the minutes.2 hours 23 minutes
Check. Check: 2 hours is 120 minutes, and 23 more is 143.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Change 4 hours to minutes. There are 60 minutes in 1 hour.4 × 60 = 240
- Add the minutes. Put the extra minutes on the end.240 + 6 = 246
- Write the answer. This is the total number of minutes.246
Check. Check: 4 hours is 240 minutes, and 6 more is 246.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Change 2 hours to minutes. There are 60 minutes in 1 hour.2 × 60 = 120
- Add the minutes. Put the extra minutes on the end.120 + 47 = 167
- Write the answer. This is the total number of minutes.167
Check. Check: 2 hours is 120 minutes, and 47 more is 167.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Facts about minutes, hours and days
There are 60 minutes in an hour, 24 hours in a day and 7 days in a week.
The months have 28, 30 or 31 days. April, June, September and November have 30 days. Use these facts to solve time problems.
Key ideas
- 60 minutes in 1 hour.
- 24 hours in 1 day.
- Learn which months have 30 days.
Method. Remember there are 60 minutes in 1 hour.
- Remember how many minutes there are in 1 hour. There are 60 minutes in 1 hour.1 hour = 60 minutes
- Multiply by 3. There are 3 hours.3 × 60 = 180
- Write the answer. This is the total number of minutes.180
Check. Check: 180 ÷ 60 = 3.
Watch out. Count the hours, then multiply by 60.
Method. Remember there are 24 hours in 1 day.
- Remember how many hours there are in 1 day. There are 24 hours in 1 day.1 day = 24 hours
- Multiply by 2. There are 2 days.2 × 24 = 48
- Write the answer. This is the total number of hours.48
Check. Check: 48 ÷ 24 = 2.
Watch out. Multiply the days by 24.
Method. Know the number of days in each month.
- Think about the calendar month of April. April is one of the months with 30 days.April has 30 days
- Count the days. Count all the days in the month.30 days
- Write the answer. This is the number of days in the month.30
Check. Check: April, June, September and November have 30 days.
Watch out. Learn the months with 30 days.
Watch out
Watch out. Not every month has 30 days. July has 31 days, and so does March.
Exam tip
Grown-up tip. Ask the child to count the knuckles and gaps on one hand, to check which months have 31 days.
Exercise 8D Practice: facts about time
Non-calculatorMethod. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many hours there are in 1 day. There are 24 hours in 1 day.1 day = 24 hours
- Multiply by 7. There are 7 days.7 × 24 = 168
- Write the answer. This is the total number of hours.168
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many hours there are in 1 day. There are 24 hours in 1 day.1 day = 24 hours
- Multiply by 5. There are 5 days.5 × 24 = 120
- Write the answer. This is the total number of hours.120
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Think about the calendar month of August. Months have 28, 30 or 31 days. February is left out here.August has 31 days
- Count the days. Count all the days in the month.31 days
- Write the answer. This is the number of days in the month.31
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Think about the calendar month of June. Months have 28, 30 or 31 days. February is left out here.June has 30 days
- Count the days. Count all the days in the month.30 days
- Write the answer. This is the number of days in the month.30
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many hours there are in 1 day. There are 24 hours in 1 day.1 day = 24 hours
- Multiply by 6. There are 6 days.6 × 24 = 144
- Write the answer. This is the total number of hours.144
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many minutes there are in 1 hour. There are 60 minutes in 1 hour.1 hour = 60 minutes
- Multiply by 12. There are 12 hours.12 × 60 = 720
- Write the answer. This is the total number of minutes.720
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many hours there are in 1 day. There are 24 hours in 1 day.1 day = 24 hours
- Multiply by 1. There are 1 days.1 × 24 = 24
- Write the answer. This is the total number of hours.24
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many minutes there are in 1 hour. There are 60 minutes in 1 hour.1 hour = 60 minutes
- Multiply by 6. There are 6 hours.6 × 60 = 360
- Write the answer. This is the total number of minutes.360
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many minutes there are in 1 hour. There are 60 minutes in 1 hour.1 hour = 60 minutes
- Multiply by 11. There are 11 hours.11 × 60 = 660
- Write the answer. This is the total number of minutes.660
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Think about the calendar month of November. Months have 28, 30 or 31 days. February is left out here.November has 30 days
- Count the days. Count all the days in the month.30 days
- Write the answer. This is the number of days in the month.30
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many minutes there are in 1 hour. There are 60 minutes in 1 hour.1 hour = 60 minutes
- Multiply by 3. There are 3 hours.3 × 60 = 180
- Write the answer. This is the total number of minutes.180
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Think about the calendar month of April. Months have 28, 30 or 31 days. February is left out here.April has 30 days
- Count the days. Count all the days in the month.30 days
- Write the answer. This is the number of days in the month.30
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many hours there are in 1 day. There are 24 hours in 1 day.1 day = 24 hours
- Multiply by 2. There are 2 days.2 × 24 = 48
- Write the answer. This is the total number of hours.48
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many minutes there are in 1 hour. There are 60 minutes in 1 hour.1 hour = 60 minutes
- Multiply by 7. There are 7 hours.7 × 60 = 420
- Write the answer. This is the total number of minutes.420
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many minutes there are in 1 hour. There are 60 minutes in 1 hour.1 hour = 60 minutes
- Multiply by 4. There are 4 hours.4 × 60 = 240
- Write the answer. This is the total number of minutes.240
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many hours there are in 1 day. There are 24 hours in 1 day.1 day = 24 hours
- Multiply by 4. There are 4 days.4 × 24 = 96
- Write the answer. This is the total number of hours.96
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Finding how long between two times
To find how long between two times, count on in steps. First count the minutes to the next hour, then the whole hours, then the last minutes.
To find an end time, add the duration to the start time. Carry the minutes into the hours when they pass 60.
Key ideas
- Count on in steps: minutes to the hour, whole hours, then minutes.
- Add a duration to find the end time.
- When minutes pass 60, add an hour.
Method. Count on from the start time to the end time, in steps: minutes to the hour, whole hours, then minutes.
- Count the minutes to the next hour. Count on to 15:00.20 to 14:20 is 40 minutes to 15:00
- Count the minutes after the hour. Count on from 15:00 to 15:05.5 minutes
- Add the parts. Add the minutes together.40 + 5 = 45
- Write the duration. The duration is 45 minutes.45 minutes
Check. Check: 14:20 plus 45 minutes is 15:05.
Watch out. Count on in minutes, not in hours.
Method. Count on from the start time to the end time, in steps.
- Count the minutes to 10:00. Count on from 9:50 to 10:00.10 minutes
- Count the hour from 10:00 to 11:00. One full hour.1 hour
- Count the minutes after 11:00. Count on from 11:00 to 11:10.10 minutes
- Add the parts. Add the parts together.10 + 60 + 10 = 80 minutes
- Write the duration. 80 minutes is 1 hour 20 minutes.1 hour 20 minutes
Check. Check: 9:50 plus 1 hour 20 minutes is 11:10.
Watch out. Do not subtract 11 from 9 and 10 from 50.
Method. Add the length of the film to the start time. Carry extra minutes into the hours.
- Write the start time. It is where we begin.13:15
- Add the hour first. One hour after 13:15 is 14:15.13:15 + 1 hour = 14:15
- Add the 40 minutes. 14:15 plus 40 minutes is 14:55.14:15 + 40 minutes = 14:55
- Write the finish time. Use two digits for the hour and minutes.14:55
Check. Check: 14:55 minus 1 hour 40 minutes is 13:15.
Watch out. Add the hours first, then the minutes.
Watch out
Watch out. From 9:50 to 11:10 is 1 hour 20 minutes, not 2 hours. Count the minutes to 10:00 first, then the rest.
Exam tip
Grown-up tip. Use a clock face or a number line from the start time. Count on, and ask: “How many minutes so far?”
Exercise 8E Practice: durations and end times
Non-calculatorMethod. Add the length of the activity to the start time. Carry extra minutes into the hours.
- Write the start time. It is where we begin.17:41
- Add the duration. Add 2 hours to the start time.17:41 + 2 hours = 19:41
- Write the finish time. Use two digits for the hour and minutes.19:41
Check. Check: 2 hours before 19:41 is 17:41.
Watch out. When the minutes go past 60, add one hour and take away 60 minutes.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 21:00. Count on to the next full hour.20:20 to 21:00 is 40 minutes
- Count the whole hours up to 20:00. Each full hour is 60 minutes.-1 hours = -60 minutes
- Count the minutes from 20:00 to 20:49. Count on the last minutes.49 minutes
- Add the parts. Add the minutes from each part.40 + -60 + 49 = 29
- Write the duration. Give the answer in hours and minutes.29 minutes
Check. Check: 20:20 plus 29 minutes is 20:49.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Add the length of the activity to the start time. Carry extra minutes into the hours.
- Write the start time. It is where we begin.09:21
- Add the duration. Add 1 hour to the start time.09:21 + 1 hour = 10:21
- Write the finish time. Use two digits for the hour and minutes.10:21
Check. Check: 1 hour before 10:21 is 09:21.
Watch out. When the minutes go past 60, add one hour and take away 60 minutes.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 15:00. Count on to the next full hour.14:55 to 15:00 is 5 minutes
- Count the whole hours up to 15:00. Each full hour is 60 minutes.0 hours = 0 minutes
- Count the minutes from 15:00 to 15:55. Count on the last minutes.55 minutes
- Add the parts. Add the minutes from each part.5 + 0 + 55 = 60
- Write the duration. Give the answer in hours and minutes.1 hour
Check. Check: 14:55 plus 1 hour is 15:55.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 11:00. Count on to the next full hour.10:30 to 11:00 is 30 minutes
- Count the whole hours up to 14:00. Each full hour is 60 minutes.3 hours = 180 minutes
- Count the minutes from 14:00 to 14:18. Count on the last minutes.18 minutes
- Add the parts. Add the minutes from each part.30 + 180 + 18 = 228
- Write the duration. Give the answer in hours and minutes.3 hours 48 minutes
Check. Check: 10:30 plus 3 hours 48 minutes is 14:18.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Add the length of the activity to the start time. Carry extra minutes into the hours.
- Write the start time. It is where we begin.14:11
- Add the duration. Add 1 hour 20 minutes to the start time.14:11 + 1 hour 20 minutes = 15:31
- Write the finish time. Use two digits for the hour and minutes.15:31
Check. Check: 1 hour 20 minutes before 15:31 is 14:11.
Watch out. When the minutes go past 60, add one hour and take away 60 minutes.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 09:00. Count on to the next full hour.08:42 to 09:00 is 18 minutes
- Count the whole hours up to 09:00. Each full hour is 60 minutes.0 hours = 0 minutes
- Count the minutes from 09:00 to 09:33. Count on the last minutes.33 minutes
- Add the parts. Add the minutes from each part.18 + 0 + 33 = 51
- Write the duration. Give the answer in hours and minutes.51 minutes
Check. Check: 08:42 plus 51 minutes is 09:33.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 18:00. Count on to the next full hour.17:46 to 18:00 is 14 minutes
- Count the whole hours up to 19:00. Each full hour is 60 minutes.1 hour = 60 minutes
- Count the minutes from 19:00 to 19:21. Count on the last minutes.21 minutes
- Add the parts. Add the minutes from each part.14 + 60 + 21 = 95
- Write the duration. Give the answer in hours and minutes.1 hour 35 minutes
Check. Check: 17:46 plus 1 hour 35 minutes is 19:21.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the whole hours up to 20:00. Each full hour is 60 minutes.2 hours = 120 minutes
- Count the minutes from 20:00 to 20:00. Count on the last minutes.0 minutes
- Add the parts. Add the minutes from each part.0 + 120 + 0 = 120
- Write the duration. Give the answer in hours and minutes.2 hours
Check. Check: 18:00 plus 2 hours is 20:00.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 18:00. Count on to the next full hour.17:21 to 18:00 is 39 minutes
- Count the whole hours up to 19:00. Each full hour is 60 minutes.1 hour = 60 minutes
- Count the minutes from 19:00 to 19:26. Count on the last minutes.26 minutes
- Add the parts. Add the minutes from each part.39 + 60 + 26 = 125
- Write the duration. Give the answer in hours and minutes.2 hours 5 minutes
Check. Check: 17:21 plus 2 hours 5 minutes is 19:26.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Add the length of the activity to the start time. Carry extra minutes into the hours.
- Write the start time. It is where we begin.13:51
- Add the duration. Add 1 hour 45 minutes to the start time.13:51 + 1 hour 45 minutes = 15:36
- Write the finish time. Use two digits for the hour and minutes.15:36
Check. Check: 1 hour 45 minutes before 15:36 is 13:51.
Watch out. When the minutes go past 60, add one hour and take away 60 minutes.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 10:00. Count on to the next full hour.09:10 to 10:00 is 50 minutes
- Count the whole hours up to 09:00. Each full hour is 60 minutes.-1 hours = -60 minutes
- Count the minutes from 09:00 to 09:35. Count on the last minutes.35 minutes
- Add the parts. Add the minutes from each part.50 + -60 + 35 = 25
- Write the duration. Give the answer in hours and minutes.25 minutes
Check. Check: 09:10 plus 25 minutes is 09:35.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 18:00. Count on to the next full hour.17:57 to 18:00 is 3 minutes
- Count the whole hours up to 20:00. Each full hour is 60 minutes.2 hours = 120 minutes
- Count the minutes from 20:00 to 20:29. Count on the last minutes.29 minutes
- Add the parts. Add the minutes from each part.3 + 120 + 29 = 152
- Write the duration. Give the answer in hours and minutes.2 hours 32 minutes
Check. Check: 17:57 plus 2 hours 32 minutes is 20:29.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 20:00. Count on to the next full hour.19:13 to 20:00 is 47 minutes
- Count the whole hours up to 23:00. Each full hour is 60 minutes.3 hours = 180 minutes
- Count the minutes from 23:00 to 23:04. Count on the last minutes.4 minutes
- Add the parts. Add the minutes from each part.47 + 180 + 4 = 231
- Write the duration. Give the answer in hours and minutes.3 hours 51 minutes
Check. Check: 19:13 plus 3 hours 51 minutes is 23:04.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Add the length of the activity to the start time. Carry extra minutes into the hours.
- Write the start time. It is where we begin.14:48
- Add the duration. Add 2 hours to the start time.14:48 + 2 hours = 16:48
- Write the finish time. Use two digits for the hour and minutes.16:48
Check. Check: 2 hours before 16:48 is 14:48.
Watch out. When the minutes go past 60, add one hour and take away 60 minutes.
Method. Add the length of the activity to the start time. Carry extra minutes into the hours.
- Write the start time. It is where we begin.15:25
- Add the duration. Add 1 hour 30 minutes to the start time.15:25 + 1 hour 30 minutes = 16:55
- Write the finish time. Use two digits for the hour and minutes.16:55
Check. Check: 1 hour 30 minutes before 16:55 is 15:25.
Watch out. When the minutes go past 60, add one hour and take away 60 minutes.
Chapter summary
| Skill | Method |
|---|---|
| Analogue clock | Long hand = minutes (5 per number); short hand = the hour that has passed |
| 12 and 24-hour clock | For p.m. add 12 to the hour, unless it is 12; midnight is 00:00 |
| Hours and minutes | 1 hour = 60 minutes; multiply by 60 to change hours to minutes |
| Facts | 60 minutes in an hour; 24 hours in a day; 30 or 31 days in a month |
| Durations | Count the minutes to the next hour, then the whole hours, then the minutes |
Can you…?
- I can read and write the time to the minute on an analogue clock
- I can write a time with a.m. or p.m., and on a 24-hour clock
- I can convert between hours and minutes
- I know the number of minutes in an hour, hours in a day and days in each month
- I can find the time between two times, and an end time
Key terms
- analogue clock
- a clock with hands and numbers round the face
- a.m.
- the time from midnight to noon, the morning
- p.m.
- the time from noon to midnight, the afternoon and evening
- duration
- how long something lasts
Exercise 8Z Check-up
Non-calculatorMethod. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Note the time of day. a.m. is the morning. p.m. is the afternoon.p.m.
- Change the hour. For p.m., add 12 to the hour unless it is 12. 12 a.m. is 00.1 gives 13
- Write the time. Use two digits for the hour.13:38
Check. Check: 13:38 is the same time of day as 1:38 p.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.87 ÷ 60 = 1 remainder 27
- Find the minutes left over. The remainder is the extra minutes.87 - 60 = 27
- Write the answer. Say the hours, then the minutes.1 hour 27 minutes
Check. Check: 1 hour is 60 minutes, and 27 more is 87.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Find the hour on a 12-hour clock. Subtract 12 from the hour if it is after 12. Midnight and noon are 12.18 is 6 on a 12-hour clock
- Decide a.m. or p.m. Times before 12:00 are a.m. and times from 12:00 are p.m.p.m.
- Write the time. Write the hour, the minutes, then a.m. or p.m.6:55 p.m.
Check. Check: 6:55 p.m. is the same time of day as 6:55 p.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 18:00. Count on to the next full hour.17:07 to 18:00 is 53 minutes
- Count the whole hours up to 17:00. Each full hour is 60 minutes.-1 hours = -60 minutes
- Count the minutes from 17:00 to 17:30. Count on the last minutes.30 minutes
- Add the parts. Add the minutes from each part.53 + -60 + 30 = 23
- Write the duration. Give the answer in hours and minutes.23 minutes
Check. Check: 17:07 plus 23 minutes is 17:30.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 13:00. Count on to the next full hour.12:30 to 13:00 is 30 minutes
- Count the whole hours up to 12:00. Each full hour is 60 minutes.-1 hours = -60 minutes
- Count the minutes from 12:00 to 12:50. Count on the last minutes.50 minutes
- Add the parts. Add the minutes from each part.30 + -60 + 50 = 20
- Write the duration. Give the answer in hours and minutes.20 minutes
Check. Check: 12:30 plus 20 minutes is 12:50.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Count how many whole hours there are. Every 60 minutes is 1 hour.77 ÷ 60 = 1 remainder 17
- Find the minutes left over. The remainder is the extra minutes.77 - 60 = 17
- Write the answer. Say the hours, then the minutes.1 hour 17 minutes
Check. Check: 1 hour is 60 minutes, and 17 more is 77.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Note the time of day. a.m. is the morning. p.m. is the afternoon.a.m.
- Change the hour. For p.m., add 12 to the hour unless it is 12. 12 a.m. is 00.7 gives 07
- Write the time. Use two digits for the hour.07:21
Check. Check: 07:21 is the same time of day as 7:21 a.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. Add the length of the activity to the start time. Carry extra minutes into the hours.
- Write the start time. It is where we begin.14:28
- Add the duration. Add 1 hour 45 minutes to the start time.14:28 + 1 hour 45 minutes = 16:13
- Write the finish time. Use two digits for the hour and minutes.16:13
Check. Check: 1 hour 45 minutes before 16:13 is 14:28.
Watch out. When the minutes go past 60, add one hour and take away 60 minutes.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many hours there are in 1 day. There are 24 hours in 1 day.1 day = 24 hours
- Multiply by 2. There are 2 days.2 × 24 = 48
- Write the answer. This is the total number of hours.48
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.10 fives = 50 minutes
- Count the small marks past that number. Each small mark is 1 minute.50 + 1 = 51 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 2
- Write the time. Write the hour, then a colon, then two digits for the minutes.2:51
Check. Check: the hour is 2, and the long hand shows 51 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.
Total 19 marks. Allow about 19 minutes.
Exercise 8X Practice test questions
Non-calculatorMethod. Add the length of the activity to the start time. Carry extra minutes into the hours.
- Write the start time. It is where we begin.15:43
- Add the duration. Add 2 hours to the start time.15:43 + 2 hours = 17:43
- Write the finish time. Use two digits for the hour and minutes.17:43
Check. Check: 2 hours before 17:43 is 15:43.
Watch out. When the minutes go past 60, add one hour and take away 60 minutes.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 07:00. Count on to the next full hour.06:02 to 07:00 is 58 minutes
- Count the whole hours up to 07:00. Each full hour is 60 minutes.0 hours = 0 minutes
- Count the minutes from 07:00 to 07:06. Count on the last minutes.6 minutes
- Add the parts. Add the minutes from each part.58 + 0 + 6 = 64
- Write the duration. Give the answer in hours and minutes.1 hour 4 minutes
Check. Check: 06:02 plus 1 hour 4 minutes is 07:06.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many hours there are in 1 day. There are 24 hours in 1 day.1 day = 24 hours
- Multiply by 1. There are 1 days.1 × 24 = 24
- Write the answer. This is the total number of hours.24
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. A 24-hour clock counts from 00:00 to 23:59. Add 12 to the hour for p.m. times.
- Note the time of day. a.m. is the morning. p.m. is after 12 noon.a.m.
- Change the hour. For p.m. times, add 12 to the hour, unless it is 12. For a.m. times, keep the hour, and 12 a.m. is 00.9 stays the same
- Write the time. Keep two digits for the hour and minutes.09:02
Check. Check: 09:02 is 9:02 a.m..
Watch out. 12:30 p.m. is 12:30 on a 24-hour clock, not 00:30. Midnight is 00:00.
Method. Count on from the start time to the end time, in steps: minutes to the next hour, whole hours, then minutes.
- Count the minutes to the next hour, 08:00. Count on to the next full hour.07:14 to 08:00 is 46 minutes
- Count the whole hours up to 07:00. Each full hour is 60 minutes.-1 hours = -60 minutes
- Count the minutes from 07:00 to 07:49. Count on the last minutes.49 minutes
- Add the parts. Add the minutes from each part.46 + -60 + 49 = 35
- Write the duration. Give the answer in hours and minutes.35 minutes
Check. Check: 07:14 plus 35 minutes is 07:49.
Watch out. Count the minutes to the next hour first. Do not subtract the hours and the minutes separately.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Change 1 hour to minutes. There are 60 minutes in 1 hour.1 × 60 = 60
- Add the minutes. Put the extra minutes on the end.60 + 18 = 78
- Write the answer. This is the total number of minutes.78
Check. Check: 1 hour is 60 minutes, and 18 more is 78.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. Convert between the 12-hour and 24-hour clock. The minutes stay the same.
- Find the hour on a 12-hour clock. Subtract 12 from the hour if it is after 12. Midnight and noon are 12.09 is 9 on a 12-hour clock
- Decide a.m. or p.m. Times before 12:00 are a.m. and times from 12:00 are p.m.a.m.
- Write the time. Write the hour, the minutes, then a.m. or p.m.9:24 a.m.
Check. Check: 9:24 a.m. is the same time of day as 9:24 a.m..
Watch out. The minutes never change. Only the hour changes on the 24-hour clock.
Method. There are 60 minutes in an hour. Multiply hours by 60 to change to minutes, or divide minutes by 60 to change to hours.
- Change 3 hours to minutes. There are 60 minutes in 1 hour.3 × 60 = 180
- Add the minutes. Put the extra minutes on the end.180 + 39 = 219
- Write the answer. This is the total number of minutes.219
Check. Check: 3 hours is 180 minutes, and 39 more is 219.
Watch out. Do not write 2 hours 135 minutes. Change every 60 minutes into 1 hour.
Method. Use the facts: 60 minutes in an hour, 24 hours in a day, and the number of days in each month.
- Remember how many minutes there are in 1 hour. There are 60 minutes in 1 hour.1 hour = 60 minutes
- Multiply by 10. There are 10 hours.10 × 60 = 600
- Write the answer. This is the total number of minutes.600
Check. Check the fact: 60 minutes, 24 hours, or the days in the month.
Watch out. Learn the months with 30 days: April, June, September and November. All the others have 31 days, except February.
Method. Read the minutes from the long hand, then the hour from the short hand.
- Read the minute hand, the long hand. Each number on the clock face is 5 minutes.0 fives = 0 minutes
- Count the small marks past that number. Each small mark is 1 minute.0 + 3 = 3 minutes
- Read the hour hand, the short hand. It shows the hour that has passed, so read the hour before it.the hour is 1
- Write the time. Write the hour, then a colon, then two digits for the minutes.1:03
Check. Check: the hour is 1, and the long hand shows 3 minutes.
Watch out. The short hand must be near the hour, and the long hand counts the minutes. Use two digits for minutes, like 7:05.