Decimals to tenths and hundredths
By the end of this chapter you will be able to
- Write and read decimals to two places
- Say the value of the tenths and hundredths digits
- Place a hundredths number on a 0 to 1 number line
- Compare and order decimals to hundredths
- Round decimals, and add and subtract money and lengths
You should already know
- Decimals to tenths (chapter 1)
- Fractions with the same denominator (chapter 6)
Where this leads
- Decimals and place value in more detail (a later level)
Step-by-step practice: maths (Level 5). Small steps, repeated until fluent. Content: Read and write decimals to two places, equivalent to tenths and hundredths (Y4 and Y5 paraphrase), Say the value of each digit in a decimal to hundredths (Y5 paraphrase), Compare and order decimals to two places, and write 0.5 as 0.50 (Y5 paraphrase), Round decimals to the nearest whole number, tenth and hundredth (Y5 paraphrase), Solve money and length problems with decimals to hundredths (Y5 paraphrase).
Exercise P Do you remember?
Non-calculatorMethod. Divide by 10 to find one tenth.
- Divide 50 into 10 equal parts. The bottom number tells us how many parts.50 ÷ 10 = 5
- Take one part. The top number is 1.1 × 5 = 5
- Write the answer. This is one tenth of 50.5
Check. Check: 10 × 5 = 50.
Watch out. Divide by the bottom number first.
Method. Write the whole number, then the tenths after the point.
- Write the whole number. The 3 is the whole part.3
- Write the tenths. 4/10 is 4 tenths, so the 4 goes after the point.3.4
- Write the answer. A decimal point separates the whole number from the tenths.3.4
Check. Check: 4/10 is 0.4, and 3 + 0.4 = 3.4.
Watch out. The first digit after the point is the tenths.
Method. Add the thousands, the hundreds, the tens and the ones.
- Add the ones. Work from the right.5 + 0 = 5, write 5
- Add the tens. Ten tens make one hundred, so carry 1 into the hundreds.2 + 8 = 10, write 0 and carry 1
- Add the hundreds. Include the carried 1.6 + 3 + 1 = 10, write 0 and carry 1
- Add the thousands. Include the carried 1.4 + 1 + 1 = 6
- Write the answer. This is the total.6,005
Check. Check: 6,005 - 1,380 = 4,625.
Watch out. Carry each ten into the next column.
Method. Add the top numbers and keep the bottom number.
- Add the top numbers. The bottom number stays the same.3 + 1 = 4
- Write the fraction. This is 4 quarters.4/4
- Simplify. Four quarters make one whole.1
Check. Check: 1/4 + 3/4 = 1 whole.
Watch out. A fraction with the top equal to the bottom is one whole.
Method. Compare the top numbers.
- Look at the bottom numbers. Both are eighths.Both are eighths
- Compare the top numbers. More eighths is greater.5 and 3
- Choose the greater. 5 eighths is more than 3 eighths.5/8
Check. Check: 5 parts is more than 3 parts of the same size.
Watch out. Compare the top numbers when the bottom numbers are the same.
Hundredths as decimals
A hundredth is one of 100 equal parts. Two places after the decimal point show hundredths: 7/100 = 0.07.
The first place after the point is tenths; the second place is hundredths. 3 + 4/10 + 7/100 = 3.47.
Key ideas
- Two places after the point: the first is tenths, the second is hundredths.
- 7/100 = 0.07, not 0.7.
- Put a zero in the tenths place when there are no tenths.
Method. Hundredths have two places after the decimal point.
- Look at the bottom number. The bottom number 100 means hundredths: two places after the point.7/100
- Write the digits in the two places. 7 hundredths: a 0 in the tenths place, then 7 in the hundredths place.0.07
- Write the answer. The two digits after the point are hundredths.0.07
Check. Check: 0.07 is 7 hundredths, which is 7/100.
Watch out. Keep both places. 7/100 is 0.07, not 0.7.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.3
- Write the tenths and the hundredths after the point. 4/10 is one place, and 7/100 is two places.3.47
- Write the answer. Check that each digit is in the right place.3.47
Check. Check: 3.47 = 3 + 0.4 + 0.07, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 6
- Write its value. 6 hundredths is 6/100.6/100 = 0.06
- Write the answer. The value is a decimal with the digit in the second place.0.06
Check. Check: in 4.56 the second digit after the point is 6, so the value is 6/100 = 0.06.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Watch out
Watch out. 0.7 is 7 tenths, and 0.07 is 7 hundredths. They are not the same number.
Exam tip
Grown-up tip. Use 100 small squares or 10 by 10 grid paper. Ask the child to shade 7 squares and write the decimal.
Exercise 7A Practice: hundredths as decimals
Non-calculatorMethod. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.3
- Write the tenths and the hundredths after the point. 1/10 is one place, and 6/100 is two places.3.16
- Write the answer. Check that each digit is in the right place.3.16
Check. Check: 3.16 = 3 + 0.1 + 0.06, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.5
- Write the tenths and the hundredths after the point. 7/10 is one place, and 5/100 is two places.5.75
- Write the answer. Check that each digit is in the right place.5.75
Check. Check: 5.75 = 5 + 0.7 + 0.05, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 6
- Write its value. 6 hundredths is 6/100.6/100 = 0.06
- Write the answer. The value is a decimal with the digit in the second place.0.06
Check. Check: in 3.56 the second digit after the point is 6, so the value is 6/100 = 0.06.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. Hundredths have two places after the decimal point.
- Look at the bottom number. The bottom number 100 means hundredths: two places after the point.73/100
- Write the digits in the two places. 73 hundredths: a 0 in the tenths place, then 73 in the hundredths place.0.73
- Write the answer. The two digits after the point are hundredths.0.73
Check. Check: 0.73 is 73 hundredths, which is 73/100.
Watch out. Keep both places. 7/100 is 0.07, not 0.7.
Method. Hundredths have two places after the decimal point.
- Look at the bottom number. The bottom number 100 means hundredths: two places after the point.79/100
- Write the digits in the two places. 79 hundredths: a 0 in the tenths place, then 79 in the hundredths place.0.79
- Write the answer. The two digits after the point are hundredths.0.79
Check. Check: 0.79 is 79 hundredths, which is 79/100.
Watch out. Keep both places. 7/100 is 0.07, not 0.7.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.7
- Write the tenths and the hundredths after the point. 4/10 is one place, and 8/100 is two places.7.48
- Write the answer. Check that each digit is in the right place.7.48
Check. Check: 7.48 = 7 + 0.4 + 0.08, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 3
- Write its value. 3 hundredths is 3/100.3/100 = 0.03
- Write the answer. The value is a decimal with the digit in the second place.0.03
Check. Check: in 8.03 the second digit after the point is 3, so the value is 3/100 = 0.03.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 2
- Write its value. 2 hundredths is 2/100.2/100 = 0.02
- Write the answer. The value is a decimal with the digit in the second place.0.02
Check. Check: in 5.92 the second digit after the point is 2, so the value is 2/100 = 0.02.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.5
- Write the tenths and the hundredths after the point. 7/10 is one place, and 6/100 is two places.5.76
- Write the answer. Check that each digit is in the right place.5.76
Check. Check: 5.76 = 5 + 0.7 + 0.06, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 8
- Write its value. 8 hundredths is 8/100.8/100 = 0.08
- Write the answer. The value is a decimal with the digit in the second place.0.08
Check. Check: in 9.98 the second digit after the point is 8, so the value is 8/100 = 0.08.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.8
- Write the tenths and the hundredths after the point. 7/10 is one place, and 5/100 is two places.8.75
- Write the answer. Check that each digit is in the right place.8.75
Check. Check: 8.75 = 8 + 0.7 + 0.05, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.5
- Write the tenths and the hundredths after the point. 9/10 is one place, and 4/100 is two places.5.94
- Write the answer. Check that each digit is in the right place.5.94
Check. Check: 5.94 = 5 + 0.9 + 0.04, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.2
- Write the tenths and the hundredths after the point. 8/10 is one place, and 2/100 is two places.2.82
- Write the answer. Check that each digit is in the right place.2.82
Check. Check: 2.82 = 2 + 0.8 + 0.02, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 7
- Write its value. 7 hundredths is 7/100.7/100 = 0.07
- Write the answer. The value is a decimal with the digit in the second place.0.07
Check. Check: in 2.57 the second digit after the point is 7, so the value is 7/100 = 0.07.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.2
- Write the tenths and the hundredths after the point. 5/10 is one place, and 9/100 is two places.2.59
- Write the answer. Check that each digit is in the right place.2.59
Check. Check: 2.59 = 2 + 0.5 + 0.09, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.3
- Write the tenths and the hundredths after the point. 1/10 is one place, and 5/100 is two places.3.15
- Write the answer. Check that each digit is in the right place.3.15
Check. Check: 3.15 = 3 + 0.1 + 0.05, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
The value of each digit, and the 0 to 1 number line
Each digit after the point has a value. In 4.56, the 5 is 5 tenths (0.5) and the 6 is 6 hundredths (0.06).
On a number line from 0 to 1, the tenths are the big marks and the hundredths are the small marks between them.
Key ideas
- The first digit after the point is tenths.
- The second digit after the point is hundredths.
- Ten hundredths make one tenth.
Method. The first digit after the point is the number of tenths.
- Find the tenths digit. It is the first digit after the decimal point.The digit is 5
- Write its value. 5 tenths is 5/10.5/10 = 0.5
- Write the answer. The value of the tenths digit is 0.1 times the digit.0.5
Check. Check: the first digit after the point is 5, so the value is 5/10 = 0.5.
Watch out. Read the digit after the point as tenths. 4 tenths is 0.4, not 4.
Method. Find the tenths, then count the hundredths beyond them.
- Find the tenths either side. Read the tenths labels to find the gap.The mark is between 0.30 and 0.40
- Count the small steps. Each small step is one hundredth.7 hundredths past 0.30
- Write the decimal. Two places after the point.0.37
Check. Check: 0.37 is 37 hundredths, which is 37/100.
Watch out. There are ten small steps between two tenths marks, so each small step is a hundredth.
Method. Find the tenths, then count the hundredths beyond them.
- Find the tenths either side. Read the tenths labels to find the gap.The mark is between 0.60 and 0.70
- Count the small steps. Each small step is one hundredth.4 hundredths past 0.60
- Write the decimal. Two places after the point.0.64
Check. Check: 0.64 is 64 hundredths, which is 64/100.
Watch out. There are ten small steps between two tenths marks, so each small step is a hundredth.
Watch out
Watch out. The 5 in 4.56 is 0.5, not 5. The value depends on the place it is in.
Exam tip
Grown-up tip. Ask: “How many small steps are between 0.3 and 0.4?” The answer is ten, so each step is a hundredth.
Exercise 7B Practice: digits and the number line
Non-calculatorMethod. Find the tenths, then count the hundredths beyond them.
- Find the tenths either side. Read the tenths labels to find the gap.The mark is between 0.90 and 1.00
- Count the small steps. Each small step is one hundredth.6 hundredths past 0.90
- Write the decimal. Two places after the point.0.96
Check. Check: 0.96 is 96 hundredths, which is 96/100.
Watch out. There are ten small steps between two tenths marks, so each small step is a hundredth.
Method. Find the tenths, then count the hundredths beyond them.
- Find the tenths either side. Read the tenths labels to find the gap.The mark is between 0.90 and 1.00
- Count the small steps. Each small step is one hundredth.9 hundredths past 0.90
- Write the decimal. Two places after the point.0.99
Check. Check: 0.99 is 99 hundredths, which is 99/100.
Watch out. There are ten small steps between two tenths marks, so each small step is a hundredth.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 1
- Write its value. 1 hundredths is 1/100.1/100 = 0.01
- Write the answer. The value is a decimal with the digit in the second place.0.01
Check. Check: in 7.71 the second digit after the point is 1, so the value is 1/100 = 0.01.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. Find the tenths, then count the hundredths beyond them.
- Find the tenths either side. Read the tenths labels to find the gap.The mark is between 0.20 and 0.30
- Count the small steps. Each small step is one hundredth.6 hundredths past 0.20
- Write the decimal. Two places after the point.0.26
Check. Check: 0.26 is 26 hundredths, which is 26/100.
Watch out. There are ten small steps between two tenths marks, so each small step is a hundredth.
Method. The first digit after the point is the number of tenths.
- Find the tenths digit. It is the first digit after the decimal point.The digit is 2
- Write its value. 2 tenths is 2/10.2/10 = 0.2
- Write the answer. The value of the tenths digit is 0.1 times the digit.0.2
Check. Check: the first digit after the point is 2, so the value is 2/10 = 0.2.
Watch out. Read the digit after the point as tenths. 4 tenths is 0.4, not 4.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 4
- Write its value. 4 hundredths is 4/100.4/100 = 0.04
- Write the answer. The value is a decimal with the digit in the second place.0.04
Check. Check: in 7.44 the second digit after the point is 4, so the value is 4/100 = 0.04.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. The first digit after the point is the number of tenths.
- Find the tenths digit. It is the first digit after the decimal point.The digit is 6
- Write its value. 6 tenths is 6/10.6/10 = 0.6
- Write the answer. The value of the tenths digit is 0.1 times the digit.0.6
Check. Check: the first digit after the point is 6, so the value is 6/10 = 0.6.
Watch out. Read the digit after the point as tenths. 4 tenths is 0.4, not 4.
Method. The first digit after the point is the number of tenths.
- Find the tenths digit. It is the first digit after the decimal point.The digit is 2
- Write its value. 2 tenths is 2/10.2/10 = 0.2
- Write the answer. The value of the tenths digit is 0.1 times the digit.0.2
Check. Check: the first digit after the point is 2, so the value is 2/10 = 0.2.
Watch out. Read the digit after the point as tenths. 4 tenths is 0.4, not 4.
Method. The first digit after the point is the number of tenths.
- Find the tenths digit. It is the first digit after the decimal point.The digit is 7
- Write its value. 7 tenths is 7/10.7/10 = 0.7
- Write the answer. The value of the tenths digit is 0.1 times the digit.0.7
Check. Check: the first digit after the point is 7, so the value is 7/10 = 0.7.
Watch out. Read the digit after the point as tenths. 4 tenths is 0.4, not 4.
Method. The first digit after the point is the number of tenths.
- Find the tenths digit. It is the first digit after the decimal point.The digit is 8
- Write its value. 8 tenths is 8/10.8/10 = 0.8
- Write the answer. The value of the tenths digit is 0.1 times the digit.0.8
Check. Check: the first digit after the point is 8, so the value is 8/10 = 0.8.
Watch out. Read the digit after the point as tenths. 4 tenths is 0.4, not 4.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 5
- Write its value. 5 hundredths is 5/100.5/100 = 0.05
- Write the answer. The value is a decimal with the digit in the second place.0.05
Check. Check: in 4.35 the second digit after the point is 5, so the value is 5/100 = 0.05.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. The first digit after the point is the number of tenths.
- Find the tenths digit. It is the first digit after the decimal point.The digit is 7
- Write its value. 7 tenths is 7/10.7/10 = 0.7
- Write the answer. The value of the tenths digit is 0.1 times the digit.0.7
Check. Check: the first digit after the point is 7, so the value is 7/10 = 0.7.
Watch out. Read the digit after the point as tenths. 4 tenths is 0.4, not 4.
Method. The first digit after the point is the number of tenths.
- Find the tenths digit. It is the first digit after the decimal point.The digit is 1
- Write its value. 1 tenths is 1/10.1/10 = 0.1
- Write the answer. The value of the tenths digit is 0.1 times the digit.0.1
Check. Check: the first digit after the point is 1, so the value is 1/10 = 0.1.
Watch out. Read the digit after the point as tenths. 4 tenths is 0.4, not 4.
Method. The first digit after the point is the number of tenths.
- Find the tenths digit. It is the first digit after the decimal point.The digit is 4
- Write its value. 4 tenths is 4/10.4/10 = 0.4
- Write the answer. The value of the tenths digit is 0.1 times the digit.0.4
Check. Check: the first digit after the point is 4, so the value is 4/10 = 0.4.
Watch out. Read the digit after the point as tenths. 4 tenths is 0.4, not 4.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 3
- Write its value. 3 hundredths is 3/100.3/100 = 0.03
- Write the answer. The value is a decimal with the digit in the second place.0.03
Check. Check: in 1.03 the second digit after the point is 3, so the value is 3/100 = 0.03.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 7
- Write its value. 7 hundredths is 7/100.7/100 = 0.07
- Write the answer. The value is a decimal with the digit in the second place.0.07
Check. Check: in 5.37 the second digit after the point is 7, so the value is 7/100 = 0.07.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Equal decimals, comparing and ordering
Adding a zero at the end of a decimal does not change its value. 0.5 = 0.50, because 5 tenths is the same as 50 hundredths.
To compare decimals, look at the whole numbers, then the tenths, then the hundredths.
Key ideas
- A zero at the end does not change the value: 0.5 = 0.50.
- Compare the whole numbers first, then tenths, then hundredths.
- Order from the smallest by comparing each place.
Method. A zero at the end of a decimal does not change its value.
- Add a zero at the end. Adding a zero after the last digit does not change the value.0.5 = 0.50
- Compare the two numbers. The tenths digit and the zero in the hundredths are both empty places.0.50 = 0.5
- Write the answer. They are equal; the zero only shows that there are no hundredths.0.50
Check. Check: 5/10 = 50/100.
Watch out. 0.5 and 0.50 are equal. The zero at the end does not make the number bigger.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.0 and 0
- Compare the tenths. If the whole numbers match, the tenths decide.4 and 5 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.5 and 0 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.0.50
Check. Check: 0.50 is 50 hundredths and 0.45 is 45 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Compare the whole numbers, then the tenths, then the hundredths.
- Compare the whole numbers. Put the smallest whole number first.0, 0, 0, 4
- Compare the tenths and hundredths. Use the next places to put the rest in order.0.47, 0.04, 0.50, 4.05
- Write the list smallest first. Check each pair in order.0.04, 0.47, 0.50, 4.05
Check. Check: each number is smaller than the one after it.
Watch out. Do not order by the number of digits. Compare the places from the left.
Watch out
Watch out. 0.45 is less than 0.5, even though 45 is more than 5. Compare the tenths first.
Exam tip
Grown-up tip. Ask: “Which is greater, 0.6 or 0.58?” Then ask why the tenths decide before the hundredths.
Exercise 7C Practice: equal decimals, comparing and ordering
Non-calculatorMethod. A zero at the end of a decimal does not change its value.
- Add a zero at the end. Adding a zero after the last digit does not change the value.5.6 = 5.60
- Compare the two numbers. The tenths digit and the zero in the hundredths are both empty places.5.60 = 5.6
- Write the answer. They are equal; the zero only shows that there are no hundredths.5.60
Check. Check: 56/10 = 560/100.
Watch out. 0.5 and 0.50 are equal. The zero at the end does not make the number bigger.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.5 and 6
- Compare the tenths. If the whole numbers match, the tenths decide.9 and 7 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.4 and 3 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.6.73
Check. Check: 6.73 is 673 hundredths and 5.94 is 594 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.6 and 2
- Compare the tenths. If the whole numbers match, the tenths decide.2 and 7 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.3 and 9 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.6.23
Check. Check: 6.23 is 623 hundredths and 2.79 is 279 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Compare the whole numbers, then the tenths, then the hundredths.
- Compare the whole numbers. Put the smallest whole number first.6, 2, 3, 9
- Compare the tenths and hundredths. Use the next places to put the rest in order.6.97, 2.74, 3.52, 9.82
- Write the list smallest first. Check each pair in order.2.74, 3.52, 6.97, 9.82
Check. Check: each number is smaller than the one after it.
Watch out. Do not order by the number of digits. Compare the places from the left.
Method. Compare the whole numbers, then the tenths, then the hundredths.
- Compare the whole numbers. Put the smallest whole number first.8, 4, 8, 4
- Compare the tenths and hundredths. Use the next places to put the rest in order.8.29, 4.48, 8.84, 4.20
- Write the list smallest first. Check each pair in order.4.20, 4.48, 8.29, 8.84
Check. Check: each number is smaller than the one after it.
Watch out. Do not order by the number of digits. Compare the places from the left.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.3 and 3
- Compare the tenths. If the whole numbers match, the tenths decide.6 and 4 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.8 and 1 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.3.68
Check. Check: 3.68 is 368 hundredths and 3.41 is 341 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Compare the whole numbers, then the tenths, then the hundredths.
- Compare the whole numbers. Put the smallest whole number first.5, 7, 8, 7
- Compare the tenths and hundredths. Use the next places to put the rest in order.5.60, 7.33, 8.61, 7.56
- Write the list smallest first. Check each pair in order.5.60, 7.33, 7.56, 8.61
Check. Check: each number is smaller than the one after it.
Watch out. Do not order by the number of digits. Compare the places from the left.
Method. A zero at the end of a decimal does not change its value.
- Add a zero at the end. Adding a zero after the last digit does not change the value.9.1 = 9.10
- Compare the two numbers. The tenths digit and the zero in the hundredths are both empty places.9.10 = 9.1
- Write the answer. They are equal; the zero only shows that there are no hundredths.9.10
Check. Check: 91/10 = 910/100.
Watch out. 0.5 and 0.50 are equal. The zero at the end does not make the number bigger.
Method. Compare the whole numbers, then the tenths, then the hundredths.
- Compare the whole numbers. Put the smallest whole number first.2, 6, 8, 6
- Compare the tenths and hundredths. Use the next places to put the rest in order.2.13, 6.78, 8.67, 6.07
- Write the list smallest first. Check each pair in order.2.13, 6.07, 6.78, 8.67
Check. Check: each number is smaller than the one after it.
Watch out. Do not order by the number of digits. Compare the places from the left.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.8 and 3
- Compare the tenths. If the whole numbers match, the tenths decide.1 and 1 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.1 and 2 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.8.11
Check. Check: 8.11 is 811 hundredths and 3.12 is 312 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Compare the whole numbers, then the tenths, then the hundredths.
- Compare the whole numbers. Put the smallest whole number first.6, 4, 2, 4
- Compare the tenths and hundredths. Use the next places to put the rest in order.6.87, 4.11, 2.99, 4.08
- Write the list smallest first. Check each pair in order.2.99, 4.08, 4.11, 6.87
Check. Check: each number is smaller than the one after it.
Watch out. Do not order by the number of digits. Compare the places from the left.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.6 and 8
- Compare the tenths. If the whole numbers match, the tenths decide.4 and 4 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.3 and 3 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.8.43
Check. Check: 8.43 is 843 hundredths and 6.43 is 643 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.1 and 3
- Compare the tenths. If the whole numbers match, the tenths decide.9 and 2 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.1 and 3 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.3.23
Check. Check: 3.23 is 323 hundredths and 1.91 is 191 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.4 and 6
- Compare the tenths. If the whole numbers match, the tenths decide.2 and 6 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.9 and 8 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.6.68
Check. Check: 6.68 is 668 hundredths and 4.29 is 429 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.8 and 5
- Compare the tenths. If the whole numbers match, the tenths decide.1 and 2 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.4 and 5 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.8.14
Check. Check: 8.14 is 814 hundredths and 5.25 is 525 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.2 and 5
- Compare the tenths. If the whole numbers match, the tenths decide.3 and 2 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.4 and 7 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.5.27
Check. Check: 5.27 is 527 hundredths and 2.34 is 234 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Rounding decimals
Look at the digit after the place you are rounding to. 5 or more: round up. 4 or less: round down.
To round to the nearest tenth, look at the hundredths. To round to the nearest whole number, look at the tenths.
Key ideas
- Round to the nearest whole number: look at the tenths digit.
- Round to the nearest tenth: look at the hundredths digit.
- Round to the nearest hundredth: look at the thousandths digit.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the tenths digit. This digit decides whether to round up or down.The digit is 4
- Decide. 5 or more: round up. 4 or less: round down.4 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.3
Check. Check: 3 is the closest number with the right number of places to 3.460.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the hundredths digit. This digit decides whether to round up or down.The digit is 6
- Decide. 5 or more: round up. 4 or less: round down.6 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.4.6
Check. Check: 4.6 is the closest number with the right number of places to 4.560.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the thousandths digit. This digit decides whether to round up or down.The digit is 6
- Decide. 5 or more: round up. 4 or less: round down.6 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.4.88
Check. Check: 4.88 is the closest number with the right number of places to 4.876.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Watch out
Watch out. 3.46 to the nearest tenth is 3.5, not 3.4. Look at the hundredths digit, which is 6.
Exam tip
Grown-up tip. Ask: “Which digit decides? Is it 5 or more?” before the child writes the rounded number.
Exercise 7D Practice: rounding decimals
Non-calculatorMethod. Look at the digit after the place you are rounding to, then decide.
- Look at the hundredths digit. This digit decides whether to round up or down.The digit is 5
- Decide. 5 or more: round up. 4 or less: round down.5 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.1.4
Check. Check: 1.4 is the closest number with the right number of places to 1.356.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the tenths digit. This digit decides whether to round up or down.The digit is 3
- Decide. 5 or more: round up. 4 or less: round down.3 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.6
Check. Check: 6 is the closest number with the right number of places to 6.304.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the hundredths digit. This digit decides whether to round up or down.The digit is 8
- Decide. 5 or more: round up. 4 or less: round down.8 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.6.6
Check. Check: 6.6 is the closest number with the right number of places to 6.581.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the hundredths digit. This digit decides whether to round up or down.The digit is 9
- Decide. 5 or more: round up. 4 or less: round down.9 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.7.1
Check. Check: 7.1 is the closest number with the right number of places to 7.097.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the tenths digit. This digit decides whether to round up or down.The digit is 8
- Decide. 5 or more: round up. 4 or less: round down.8 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.3
Check. Check: 3 is the closest number with the right number of places to 2.876.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the tenths digit. This digit decides whether to round up or down.The digit is 3
- Decide. 5 or more: round up. 4 or less: round down.3 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.6
Check. Check: 6 is the closest number with the right number of places to 6.323.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the thousandths digit. This digit decides whether to round up or down.The digit is 2
- Decide. 5 or more: round up. 4 or less: round down.2 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.9.34
Check. Check: 9.34 is the closest number with the right number of places to 9.342.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the thousandths digit. This digit decides whether to round up or down.The digit is 9
- Decide. 5 or more: round up. 4 or less: round down.9 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.3.40
Check. Check: 3.40 is the closest number with the right number of places to 3.399.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the thousandths digit. This digit decides whether to round up or down.The digit is 4
- Decide. 5 or more: round up. 4 or less: round down.4 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.2.00
Check. Check: 2.00 is the closest number with the right number of places to 2.004.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the thousandths digit. This digit decides whether to round up or down.The digit is 9
- Decide. 5 or more: round up. 4 or less: round down.9 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.1.63
Check. Check: 1.63 is the closest number with the right number of places to 1.629.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the hundredths digit. This digit decides whether to round up or down.The digit is 3
- Decide. 5 or more: round up. 4 or less: round down.3 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.9.1
Check. Check: 9.1 is the closest number with the right number of places to 9.131.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the hundredths digit. This digit decides whether to round up or down.The digit is 0
- Decide. 5 or more: round up. 4 or less: round down.0 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.7.9
Check. Check: 7.9 is the closest number with the right number of places to 7.908.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the thousandths digit. This digit decides whether to round up or down.The digit is 7
- Decide. 5 or more: round up. 4 or less: round down.7 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.8.79
Check. Check: 8.79 is the closest number with the right number of places to 8.787.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the hundredths digit. This digit decides whether to round up or down.The digit is 1
- Decide. 5 or more: round up. 4 or less: round down.1 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.2.3
Check. Check: 2.3 is the closest number with the right number of places to 2.312.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the tenths digit. This digit decides whether to round up or down.The digit is 6
- Decide. 5 or more: round up. 4 or less: round down.6 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.5
Check. Check: 5 is the closest number with the right number of places to 4.649.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the thousandths digit. This digit decides whether to round up or down.The digit is 8
- Decide. 5 or more: round up. 4 or less: round down.8 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.3.53
Check. Check: 3.53 is the closest number with the right number of places to 3.528.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Adding and subtracting money and lengths
Line up the decimal points, so that pounds are under pounds and pence are under pence. Add or subtract column by column, from the right.
Always write two places for pence: £5.00, not £5.
Key ideas
- Line up the decimal points.
- Add or subtract the pence first, then the pounds.
- Keep the unit in the answer.
Method. Line up the decimal points and add in columns. Keep the pound sign and two places for pence.
- Line up the decimal points. Write the pounds and pence in columns.3.46 + 2.85
- Add the pence first. Carry any ten pence into the pounds.46 + 85 = 131 pence
- Add the pounds. Include any carried pounds.3 + 2 = 6 pounds
- Write the answer with the pound sign. Always write two places for the pence.£6.31
Check. Check: £6.31 - £2.85 = £3.46.
Watch out. Always write two digits for the pence: £5.00, not £5.
Method. Line up the decimal points, then subtract the pence and the pounds.
- Line up the decimal points. Write the amounts one above the other.5.00 - 2.36
- Subtract the pence, exchanging if needed. Take a pound to make 100 pence if the pence are too few.0 - 36 = 64 pence
- Subtract the pounds. Include any exchanged pound.2 pounds
- Write the answer with the pound sign. Two places for the pence.£2.64
Check. Check: £2.64 + £2.36 = £5.00.
Watch out. Always keep the decimal points in a line. Write £2.64, not £2.6.
Method. Line up the decimal points, then add in columns, keeping the unit.
- Line up the decimal points. Add the metres and the centimetres in the right places.1.25 + 0.60
- Add the hundredths and tenths. Carry where needed.85 hundredths in total
- Write the total length with the unit. Give the answer in metres, to two places.1.85 m
Check. Check: 1.85 - 0.60 = 1.25.
Watch out. Write the unit in the answer: 1.85 m, not 1.85.
Watch out
Watch out. £5.00 - £2.36 is £2.64. Exchange a pound to make 100 pence first.
Exam tip
Grown-up tip. Use real coins. Ask the child to pay £2.36 with £5 and count the change.
Exercise 7E Practice: money and lengths
Non-calculatorMethod. Line up the decimal points and add in columns. Keep the pound sign and two places for pence.
- Line up the decimal points. Write the pounds and pence in columns.5.41 + 4.82
- Add the pence first. Carry any ten pence into the pounds.41 + 82 = 123 pence
- Add the pounds. Include any carried pounds.5 + 4 = 10 pounds
- Write the answer with the pound sign. Always write two places for the pence.£10.23
Check. Check: £10.23 - £4.82 = £5.41.
Watch out. Always write two digits for the pence: £5.00, not £5.
Method. Line up the decimal points, then add in columns, keeping the unit.
- Line up the decimal points. Add the metres and the centimetres in the right places.2.33 + 1.91
- Add the hundredths and tenths. Carry where needed.24 hundredths in total
- Write the total length with the unit. Give the answer in metres, to two places.4.24 m
Check. Check: 4.24 - 1.91 = 2.33.
Watch out. Write the unit in the answer: 1.85 m, not 1.85.
Method. Line up the decimal points, then add in columns, keeping the unit.
- Line up the decimal points. Add the metres and the centimetres in the right places.1.56 + 0.95
- Add the hundredths and tenths. Carry where needed.51 hundredths in total
- Write the total length with the unit. Give the answer in metres, to two places.2.51 m
Check. Check: 2.51 - 0.95 = 1.56.
Watch out. Write the unit in the answer: 1.85 m, not 1.85.
Method. Line up the decimal points, then add in columns, keeping the unit.
- Line up the decimal points. Add the metres and the centimetres in the right places.1.10 + 1.60
- Add the hundredths and tenths. Carry where needed.70 hundredths in total
- Write the total length with the unit. Give the answer in metres, to two places.2.70 m
Check. Check: 2.70 - 1.60 = 1.10.
Watch out. Write the unit in the answer: 1.85 m, not 1.85.
Method. Line up the decimal points, then subtract the pence and the pounds.
- Line up the decimal points. Write the amounts one above the other.7.37 - 3.77
- Subtract the pence, exchanging if needed. Take a pound to make 100 pence if the pence are too few.37 - 77 = 60 pence
- Subtract the pounds. Include any exchanged pound.3 pounds
- Write the answer with the pound sign. Two places for the pence.£3.60
Check. Check: £3.60 + £3.77 = £7.37.
Watch out. Always keep the decimal points in a line. Write £2.64, not £2.6.
Method. Line up the decimal points, then add in columns, keeping the unit.
- Line up the decimal points. Add the metres and the centimetres in the right places.1.55 + 0.83
- Add the hundredths and tenths. Carry where needed.38 hundredths in total
- Write the total length with the unit. Give the answer in metres, to two places.2.38 m
Check. Check: 2.38 - 0.83 = 1.55.
Watch out. Write the unit in the answer: 1.85 m, not 1.85.
Method. Line up the decimal points and add in columns. Keep the pound sign and two places for pence.
- Line up the decimal points. Write the pounds and pence in columns.2.14 + 6.92
- Add the pence first. Carry any ten pence into the pounds.14 + 92 = 106 pence
- Add the pounds. Include any carried pounds.2 + 6 = 9 pounds
- Write the answer with the pound sign. Always write two places for the pence.£9.06
Check. Check: £9.06 - £6.92 = £2.14.
Watch out. Always write two digits for the pence: £5.00, not £5.
Method. Line up the decimal points, then subtract the pence and the pounds.
- Line up the decimal points. Write the amounts one above the other.5.58 - 2.34
- Subtract the pence, exchanging if needed. Take a pound to make 100 pence if the pence are too few.58 - 34 = 24 pence
- Subtract the pounds. Include any exchanged pound.3 pounds
- Write the answer with the pound sign. Two places for the pence.£3.24
Check. Check: £3.24 + £2.34 = £5.58.
Watch out. Always keep the decimal points in a line. Write £2.64, not £2.6.
Method. Line up the decimal points and add in columns. Keep the pound sign and two places for pence.
- Line up the decimal points. Write the pounds and pence in columns.7.67 + 3.79
- Add the pence first. Carry any ten pence into the pounds.67 + 79 = 146 pence
- Add the pounds. Include any carried pounds.7 + 3 = 11 pounds
- Write the answer with the pound sign. Always write two places for the pence.£11.46
Check. Check: £11.46 - £3.79 = £7.67.
Watch out. Always write two digits for the pence: £5.00, not £5.
Method. Line up the decimal points, then add in columns, keeping the unit.
- Line up the decimal points. Add the metres and the centimetres in the right places.1.50 + 0.22
- Add the hundredths and tenths. Carry where needed.72 hundredths in total
- Write the total length with the unit. Give the answer in metres, to two places.1.72 m
Check. Check: 1.72 - 0.22 = 1.50.
Watch out. Write the unit in the answer: 1.85 m, not 1.85.
Method. Line up the decimal points, then subtract the pence and the pounds.
- Line up the decimal points. Write the amounts one above the other.5.02 - 3.57
- Subtract the pence, exchanging if needed. Take a pound to make 100 pence if the pence are too few.2 - 57 = 45 pence
- Subtract the pounds. Include any exchanged pound.1 pounds
- Write the answer with the pound sign. Two places for the pence.£1.45
Check. Check: £1.45 + £3.57 = £5.02.
Watch out. Always keep the decimal points in a line. Write £2.64, not £2.6.
Method. Line up the decimal points and add in columns. Keep the pound sign and two places for pence.
- Line up the decimal points. Write the pounds and pence in columns.4.70 + 4.63
- Add the pence first. Carry any ten pence into the pounds.70 + 63 = 133 pence
- Add the pounds. Include any carried pounds.4 + 4 = 9 pounds
- Write the answer with the pound sign. Always write two places for the pence.£9.33
Check. Check: £9.33 - £4.63 = £4.70.
Watch out. Always write two digits for the pence: £5.00, not £5.
Method. Line up the decimal points and add in columns. Keep the pound sign and two places for pence.
- Line up the decimal points. Write the pounds and pence in columns.5.96 + 1.63
- Add the pence first. Carry any ten pence into the pounds.96 + 63 = 159 pence
- Add the pounds. Include any carried pounds.5 + 1 = 7 pounds
- Write the answer with the pound sign. Always write two places for the pence.£7.59
Check. Check: £7.59 - £1.63 = £5.96.
Watch out. Always write two digits for the pence: £5.00, not £5.
Method. Line up the decimal points and add in columns. Keep the pound sign and two places for pence.
- Line up the decimal points. Write the pounds and pence in columns.3.55 + 4.40
- Add the pence first. Carry any ten pence into the pounds.55 + 40 = 95 pence
- Add the pounds. Include any carried pounds.3 + 4 = 7 pounds
- Write the answer with the pound sign. Always write two places for the pence.£7.95
Check. Check: £7.95 - £4.40 = £3.55.
Watch out. Always write two digits for the pence: £5.00, not £5.
Method. Line up the decimal points, then add in columns, keeping the unit.
- Line up the decimal points. Add the metres and the centimetres in the right places.1.74 + 0.66
- Add the hundredths and tenths. Carry where needed.40 hundredths in total
- Write the total length with the unit. Give the answer in metres, to two places.2.40 m
Check. Check: 2.40 - 0.66 = 1.74.
Watch out. Write the unit in the answer: 1.85 m, not 1.85.
Method. Line up the decimal points and add in columns. Keep the pound sign and two places for pence.
- Line up the decimal points. Write the pounds and pence in columns.4.64 + 6.49
- Add the pence first. Carry any ten pence into the pounds.64 + 49 = 113 pence
- Add the pounds. Include any carried pounds.4 + 6 = 11 pounds
- Write the answer with the pound sign. Always write two places for the pence.£11.13
Check. Check: £11.13 - £6.49 = £4.64.
Watch out. Always write two digits for the pence: £5.00, not £5.
Chapter summary
| Skill | Method |
|---|---|
| Hundredths | Two places after the point: tenths, then hundredths; 7/100 = 0.07 |
| Digit values | The value depends on the place: 4.56 has 5 tenths and 6 hundredths |
| Equal decimals | A zero at the end does not change the value: 0.5 = 0.50 |
| Comparing | Whole numbers, then tenths, then hundredths |
| Rounding | Look at the digit after the place; 5 or more rounds up |
| Money and lengths | Line up the points; add or subtract; keep two places for pence |
Can you…?
- I can read and write decimals to two places
- I can say the value of the tenths and hundredths digits
- I can place a hundredths number on a 0 to 1 number line
- I can compare and order decimals to hundredths, and write 0.5 as 0.50
- I can round decimals to the nearest whole number, tenth and hundredth
- I can add and subtract money and lengths with decimals
Key terms
- hundredth
- one of 100 equal parts; written as 0.01 or as 1/100
- decimal point
- the dot that separates the whole number from the parts
- round
- make a number simpler, to the nearest place
- value
- what a digit is worth because of its place
Exercise 7Z Check-up
Non-calculatorMethod. Line up the decimal points and add in columns. Keep the pound sign and two places for pence.
- Line up the decimal points. Write the pounds and pence in columns.1.40 + 1.91
- Add the pence first. Carry any ten pence into the pounds.40 + 91 = 131 pence
- Add the pounds. Include any carried pounds.1 + 1 = 3 pounds
- Write the answer with the pound sign. Always write two places for the pence.£3.31
Check. Check: £3.31 - £1.91 = £1.40.
Watch out. Always write two digits for the pence: £5.00, not £5.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the hundredths digit. This digit decides whether to round up or down.The digit is 3
- Decide. 5 or more: round up. 4 or less: round down.3 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.3.3
Check. Check: 3.3 is the closest number with the right number of places to 3.333.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.9
- Write the tenths and the hundredths after the point. 8/10 is one place, and 3/100 is two places.9.83
- Write the answer. Check that each digit is in the right place.9.83
Check. Check: 9.83 = 9 + 0.8 + 0.03, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the tenths digit. This digit decides whether to round up or down.The digit is 1
- Decide. 5 or more: round up. 4 or less: round down.1 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.4
Check. Check: 4 is the closest number with the right number of places to 4.170.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Find the tenths, then count the hundredths beyond them.
- Find the tenths either side. Read the tenths labels to find the gap.The mark is between 0.80 and 0.90
- Count the small steps. Each small step is one hundredth.2 hundredths past 0.80
- Write the decimal. Two places after the point.0.82
Check. Check: 0.82 is 82 hundredths, which is 82/100.
Watch out. There are ten small steps between two tenths marks, so each small step is a hundredth.
Method. Write the whole number, then one digit for the tenths and two digits for the hundredths.
- Write the whole number first. This is the part before the decimal point.2
- Write the tenths and the hundredths after the point. 3/10 is one place, and 9/100 is two places.2.39
- Write the answer. Check that each digit is in the right place.2.39
Check. Check: 2.39 = 2 + 0.3 + 0.09, when h is a single digit.
Watch out. Use two places for hundredths. The hundredths digit is the second place after the point.
Method. Find the tenths, then count the hundredths beyond them.
- Find the tenths either side. Read the tenths labels to find the gap.The mark is between 0.80 and 0.90
- Count the small steps. Each small step is one hundredth.8 hundredths past 0.80
- Write the decimal. Two places after the point.0.88
Check. Check: 0.88 is 88 hundredths, which is 88/100.
Watch out. There are ten small steps between two tenths marks, so each small step is a hundredth.
Method. Line up the decimal points, then add in columns, keeping the unit.
- Line up the decimal points. Add the metres and the centimetres in the right places.2.29 + 2.16
- Add the hundredths and tenths. Carry where needed.45 hundredths in total
- Write the total length with the unit. Give the answer in metres, to two places.4.45 m
Check. Check: 4.45 - 2.16 = 2.29.
Watch out. Write the unit in the answer: 1.85 m, not 1.85.
Method. A zero at the end of a decimal does not change its value.
- Add a zero at the end. Adding a zero after the last digit does not change the value.9.8 = 9.80
- Compare the two numbers. The tenths digit and the zero in the hundredths are both empty places.9.80 = 9.8
- Write the answer. They are equal; the zero only shows that there are no hundredths.9.80
Check. Check: 98/10 = 980/100.
Watch out. 0.5 and 0.50 are equal. The zero at the end does not make the number bigger.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 7
- Write its value. 7 hundredths is 7/100.7/100 = 0.07
- Write the answer. The value is a decimal with the digit in the second place.0.07
Check. Check: in 8.47 the second digit after the point is 7, so the value is 7/100 = 0.07.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Total 19 marks. Allow about 19 minutes.
Exercise 7X Practice test questions
Non-calculatorMethod. Compare the whole numbers, then the tenths, then the hundredths.
- Compare the whole numbers. Put the smallest whole number first.3, 3, 7, 8
- Compare the tenths and hundredths. Use the next places to put the rest in order.3.36, 3.62, 7.07, 8.81
- Write the list smallest first. Check each pair in order.3.36, 3.62, 7.07, 8.81
Check. Check: each number is smaller than the one after it.
Watch out. Do not order by the number of digits. Compare the places from the left.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the thousandths digit. This digit decides whether to round up or down.The digit is 8
- Decide. 5 or more: round up. 4 or less: round down.8 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.6.99
Check. Check: 6.99 is the closest number with the right number of places to 6.988.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Compare the digits from the left: whole numbers, then tenths, then hundredths.
- Compare the whole numbers. The bigger whole number is the bigger decimal.2 and 8
- Compare the tenths. If the whole numbers match, the tenths decide.5 and 7 tenths
- Compare the hundredths. If the tenths also match, the hundredths decide.2 and 9 hundredths
- Choose the greater number. This is the number with the larger digit in the first place they differ.8.79
Check. Check: 8.79 is 879 hundredths and 2.52 is 252 hundredths.
Watch out. Do not think 0.45 is bigger than 0.5 because 45 is bigger than 5. Compare the tenths first.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the thousandths digit. This digit decides whether to round up or down.The digit is 9
- Decide. 5 or more: round up. 4 or less: round down.9 is 5 or more, so round up
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.2.13
Check. Check: 2.13 is the closest number with the right number of places to 2.129.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. Look at the digit after the place you are rounding to, then decide.
- Look at the tenths digit. This digit decides whether to round up or down.The digit is 4
- Decide. 5 or more: round up. 4 or less: round down.4 is 4 or less, so round down
- Write the rounded number. Make the digits after the rounding place zero, or leave them out.2
Check. Check: 2 is the closest number with the right number of places to 2.472.
Watch out. Round up only on a 5 or more. Do not drop the zero from the tenths when rounding to tenths.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 5
- Write its value. 5 hundredths is 5/100.5/100 = 0.05
- Write the answer. The value is a decimal with the digit in the second place.0.05
Check. Check: in 4.55 the second digit after the point is 5, so the value is 5/100 = 0.05.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 7
- Write its value. 7 hundredths is 7/100.7/100 = 0.07
- Write the answer. The value is a decimal with the digit in the second place.0.07
Check. Check: in 1.07 the second digit after the point is 7, so the value is 7/100 = 0.07.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. The second digit after the point is the number of hundredths.
- Find the hundredths digit. It is the second digit after the decimal point.The digit is 5
- Write its value. 5 hundredths is 5/100.5/100 = 0.05
- Write the answer. The value is a decimal with the digit in the second place.0.05
Check. Check: in 2.75 the second digit after the point is 5, so the value is 5/100 = 0.05.
Watch out. The value is 0.0 with the digit after it: 0.07, not 0.7.
Method. Compare the whole numbers, then the tenths, then the hundredths.
- Compare the whole numbers. Put the smallest whole number first.1, 7, 7, 5
- Compare the tenths and hundredths. Use the next places to put the rest in order.1.84, 7.16, 7.13, 5.71
- Write the list smallest first. Check each pair in order.1.84, 5.71, 7.13, 7.16
Check. Check: each number is smaller than the one after it.
Watch out. Do not order by the number of digits. Compare the places from the left.
Method. Compare the whole numbers, then the tenths, then the hundredths.
- Compare the whole numbers. Put the smallest whole number first.7, 2, 4, 2
- Compare the tenths and hundredths. Use the next places to put the rest in order.7.19, 2.71, 4.00, 2.82
- Write the list smallest first. Check each pair in order.2.71, 2.82, 4.00, 7.19
Check. Check: each number is smaller than the one after it.
Watch out. Do not order by the number of digits. Compare the places from the left.