Comparing and ordering to 100
By the end of this chapter you will be able to
- Compare numbers with < > and =
- Order up to five numbers
- Find the greatest and least
- Find 10 more and 10 less
- Find numbers between two others on a number line
You should already know
- Tens and ones (Level 2, Chapter 2)
- Counting to 100 (Level 2, Chapter 1)
- Numbers to 20 (Level 1)
Where this leads
- Number bonds to 20 (Chapter 4)
- Adding and subtracting within 100 (Chapter 7)
Step-by-step practice: maths (Level 2). Small steps, repeated until fluent. Content: Compare two numbers up to 100 using the signs <, > and =, Put a set of up to five numbers in order, smallest to largest and largest to smallest, Find the greatest and the least number in a set, Find 1 more, 1 less, 10 more and 10 less than any number up to 100, Use a number line to find a number between two others.
Exercise P Do you remember?
Non-calculatorMethod. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.2 and 4
- Tens are different, so the tens decide. 2 tens is fewer than 4 tens.2 tens and 4 tens
- Write the sign. 29 is less than 41.<
Check. 29 < 41 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.16: 1 tens, 8: 0 tens, 12: 1 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.8
- Write the numbers in order. Check that each one fits between the ones next to it.8, 12, 16
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.24
- Change it. Add one. Count on to the next number.24 + 1 = 25
- Write the answer. 25
Check. Reverse the change: 25 - 1 gives 24.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.1, 1, 1
- Check the ones if two numbers have the same tens. The ones decide between them.13, 19, 11
- Choose the greatest. It is the biggest of the numbers in the list.19
Check. Put the others in order to check: 19 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.5 and 5
- Tens are the same, so compare the ones. Both numbers have the same ones too.0 and 0
- Write the sign. 50 is equal to 50.=
Check. 50 = 50 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Greater than, less than and equal to
The sign < means less than. The sign > means greater than.
The sign = means the two numbers are the same. The open end of the sign faces the bigger number.
Key ideas
- < means less than, > means greater than, = means equal to.
- Compare the tens first.
- If the tens are the same, compare the ones.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.3 and 5
- Tens are different, so the tens decide. 3 tens is fewer than 5 tens.3 tens and 5 tens
- Write the sign. 38 is less than 52.<
Check. 38 < 52 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.7 and 6
- Tens are different, so the tens decide. 7 tens is more than 6 tens.7 tens and 6 tens
- Write the sign. 74 is greater than 67.>
Check. 74 > 67 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.4 and 4
- Tens are the same, so compare the ones. Both numbers have the same ones too.5 and 5
- Write the sign. 45 is equal to 45.=
Check. 45 = 45 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Watch out
Watch out. Point the open end at the bigger number, like a mouth that wants the bigger one.
Exam tip
Grown-up tip. Write two numbers on cards. Hold them up and ask: “Which is bigger?” before you write the sign.
Exercise 3A Practice: comparing numbers
Non-calculatorMethod. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.6 and 6
- Tens are the same, so compare the ones. Both numbers have the same ones too.3 and 3
- Write the sign. 63 is equal to 63.=
Check. 63 = 63 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.7 and 4
- Tens are different, so the tens decide. 7 tens is more than 4 tens.7 tens and 4 tens
- Write the sign. 74 is greater than 44.>
Check. 74 > 44 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.5 and 3
- Tens are different, so the tens decide. 5 tens is more than 3 tens.5 tens and 3 tens
- Write the sign. 56 is greater than 37.>
Check. 56 > 37 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.8 and 5
- Tens are different, so the tens decide. 8 tens is more than 5 tens.8 tens and 5 tens
- Write the sign. 85 is greater than 56.>
Check. 85 > 56 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.1 and 6
- Tens are different, so the tens decide. 1 tens is fewer than 6 tens.1 tens and 6 tens
- Write the sign. 14 is less than 67.<
Check. 14 < 67 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.7 and 1
- Tens are different, so the tens decide. 7 tens is more than 1 tens.7 tens and 1 tens
- Write the sign. 74 is greater than 12.>
Check. 74 > 12 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.8 and 7
- Tens are different, so the tens decide. 8 tens is more than 7 tens.8 tens and 7 tens
- Write the sign. 81 is greater than 72.>
Check. 81 > 72 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.5 and 1
- Tens are different, so the tens decide. 5 tens is more than 1 tens.5 tens and 1 tens
- Write the sign. 56 is greater than 18.>
Check. 56 > 18 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.6 and 8
- Tens are different, so the tens decide. 6 tens is fewer than 8 tens.6 tens and 8 tens
- Write the sign. 64 is less than 82.<
Check. 64 < 82 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.8 and 7
- Tens are different, so the tens decide. 8 tens is more than 7 tens.8 tens and 7 tens
- Write the sign. 83 is greater than 79.>
Check. 83 > 79 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.7 and 4
- Tens are different, so the tens decide. 7 tens is more than 4 tens.7 tens and 4 tens
- Write the sign. 72 is greater than 40.>
Check. 72 > 40 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.1 and 6
- Tens are different, so the tens decide. 1 tens is fewer than 6 tens.1 tens and 6 tens
- Write the sign. 10 is less than 69.<
Check. 10 < 69 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.3 and 7
- Tens are different, so the tens decide. 3 tens is fewer than 7 tens.3 tens and 7 tens
- Write the sign. 30 is less than 74.<
Check. 30 < 74 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.9 and 7
- Tens are different, so the tens decide. 9 tens is more than 7 tens.9 tens and 7 tens
- Write the sign. 97 is greater than 74.>
Check. 97 > 74 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.1 and 3
- Tens are different, so the tens decide. 1 tens is fewer than 3 tens.1 tens and 3 tens
- Write the sign. 10 is less than 38.<
Check. 10 < 38 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.5 and 2
- Tens are different, so the tens decide. 5 tens is more than 2 tens.5 tens and 2 tens
- Write the sign. 55 is greater than 29.>
Check. 55 > 29 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Putting numbers in order
To put numbers in order, look at the tens first. The number with the fewest tens is the smallest.
Then look at the ones when two numbers have the same tens.
Key ideas
- Smallest to largest: the numbers get bigger.
- Largest to smallest: the numbers get smaller.
- Check your list by reading it again.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.45: 4 tens, 27: 2 tens, 63: 6 tens, 38: 3 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.27
- Write the numbers in order. Check that each one fits between the ones next to it.27, 38, 45, 63
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.81: 8 tens, 19: 1 tens, 50: 5 tens, 64: 6 tens, 33: 3 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.81
- Write the numbers in order. Check that each one fits between the ones next to it.81, 64, 50, 33, 19
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.67: 6 tens, 61: 6 tens, 76: 7 tens, 16: 1 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.16
- Write the numbers in order. Check that each one fits between the ones next to it.16, 61, 67, 76
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Watch out
Watch out. 19 is smaller than 91, even though the ones digit 9 is the same. Look at the tens first.
Exam tip
Grown-up tip. Write each number on a card and lay them in a line. Move the cards until the line goes up.
Exercise 3B Practice: putting numbers in order
Non-calculatorMethod. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.36: 3 tens, 47: 4 tens, 78: 7 tens, 68: 6 tens, 97: 9 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.36
- Write the numbers in order. Check that each one fits between the ones next to it.36, 47, 68, 78, 97
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.20: 2 tens, 97: 9 tens, 74: 7 tens, 59: 5 tens, 96: 9 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.97
- Write the numbers in order. Check that each one fits between the ones next to it.97, 96, 74, 59, 20
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.37: 3 tens, 51: 5 tens, 96: 9 tens, 46: 4 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.96
- Write the numbers in order. Check that each one fits between the ones next to it.96, 51, 46, 37
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.44: 4 tens, 35: 3 tens, 48: 4 tens, 55: 5 tens, 22: 2 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.55
- Write the numbers in order. Check that each one fits between the ones next to it.55, 48, 44, 35, 22
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.97: 9 tens, 16: 1 tens, 84: 8 tens, 11: 1 tens, 73: 7 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.97
- Write the numbers in order. Check that each one fits between the ones next to it.97, 84, 73, 16, 11
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.68: 6 tens, 91: 9 tens, 34: 3 tens, 41: 4 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.34
- Write the numbers in order. Check that each one fits between the ones next to it.34, 41, 68, 91
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.45: 4 tens, 92: 9 tens, 16: 1 tens, 34: 3 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.92
- Write the numbers in order. Check that each one fits between the ones next to it.92, 45, 34, 16
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.20: 2 tens, 16: 1 tens, 32: 3 tens, 34: 3 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.34
- Write the numbers in order. Check that each one fits between the ones next to it.34, 32, 20, 16
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.67: 6 tens, 75: 7 tens, 37: 3 tens, 58: 5 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.37
- Write the numbers in order. Check that each one fits between the ones next to it.37, 58, 67, 75
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.27: 2 tens, 66: 6 tens, 30: 3 tens, 90: 9 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.90
- Write the numbers in order. Check that each one fits between the ones next to it.90, 66, 30, 27
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.24: 2 tens, 88: 8 tens, 55: 5 tens, 41: 4 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.88
- Write the numbers in order. Check that each one fits between the ones next to it.88, 55, 41, 24
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, largest to smallest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.66: 6 tens, 78: 7 tens, 28: 2 tens, 24: 2 tens, 29: 2 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.78
- Write the numbers in order. Check that each one fits between the ones next to it.78, 66, 29, 28, 24
Check. Read the list again. Each number is smaller than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.53: 5 tens, 60: 6 tens, 94: 9 tens, 77: 7 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.53
- Write the numbers in order. Check that each one fits between the ones next to it.53, 60, 77, 94
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.33: 3 tens, 31: 3 tens, 30: 3 tens, 87: 8 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.30
- Write the numbers in order. Check that each one fits between the ones next to it.30, 31, 33, 87
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.90: 9 tens, 86: 8 tens, 30: 3 tens, 51: 5 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.30
- Write the numbers in order. Check that each one fits between the ones next to it.30, 51, 86, 90
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.15: 1 tens, 64: 6 tens, 63: 6 tens, 79: 7 tens, 78: 7 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.15
- Write the numbers in order. Check that each one fits between the ones next to it.15, 63, 64, 78, 79
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Finding the greatest and the least
The greatest number is the biggest. The least number is the smallest.
You can find them by comparing the tens, then the ones. You do not need to put every number in order.
Key ideas
- Greatest means biggest.
- Least means smallest.
- Look at the tens first.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.5, 6, 4, 5
- Check the ones if two numbers have the same tens. The ones decide between them.56, 61, 49, 58
- Choose the greatest. It is the biggest of the numbers in the list.61
Check. Put the others in order to check: 61 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.7, 2, 7, 7
- Check the ones if two numbers have the same tens. The ones decide between them.72, 27, 70, 79
- Choose the least. It is the smallest of the numbers in the list.27
Check. Put the others in order to check: 27 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.3, 8, 3, 2
- Check the ones if two numbers have the same tens. The ones decide between them.38, 83, 33, 28
- Choose the greatest. It is the biggest of the numbers in the list.83
Check. Put the others in order to check: 83 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Watch out
Watch out. The greatest number does not always have the biggest ones digit. Compare the tens first.
Exam tip
Grown-up tip. Ask: “Which is the biggest?” and “Which is the smallest?” with the same set of numbers.
Exercise 3C Practice: greatest and least
Non-calculatorMethod. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.1, 8, 6
- Check the ones if two numbers have the same tens. The ones decide between them.10, 80, 66
- Choose the least. It is the smallest of the numbers in the list.10
Check. Put the others in order to check: 10 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.8, 8, 9, 8, 6
- Check the ones if two numbers have the same tens. The ones decide between them.82, 88, 91, 87, 64
- Choose the least. It is the smallest of the numbers in the list.64
Check. Put the others in order to check: 64 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.8, 6, 9, 3, 7
- Check the ones if two numbers have the same tens. The ones decide between them.85, 63, 99, 34, 76
- Choose the greatest. It is the biggest of the numbers in the list.99
Check. Put the others in order to check: 99 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.4, 2, 5
- Check the ones if two numbers have the same tens. The ones decide between them.45, 26, 51
- Choose the greatest. It is the biggest of the numbers in the list.51
Check. Put the others in order to check: 51 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.9, 3, 4, 8
- Check the ones if two numbers have the same tens. The ones decide between them.97, 38, 46, 84
- Choose the greatest. It is the biggest of the numbers in the list.97
Check. Put the others in order to check: 97 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.5, 9, 9
- Check the ones if two numbers have the same tens. The ones decide between them.50, 93, 94
- Choose the greatest. It is the biggest of the numbers in the list.94
Check. Put the others in order to check: 94 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.2, 3, 8, 1
- Check the ones if two numbers have the same tens. The ones decide between them.29, 39, 86, 14
- Choose the greatest. It is the biggest of the numbers in the list.86
Check. Put the others in order to check: 86 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.4, 6, 1, 1, 8
- Check the ones if two numbers have the same tens. The ones decide between them.41, 63, 13, 15, 88
- Choose the greatest. It is the biggest of the numbers in the list.88
Check. Put the others in order to check: 88 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.8, 4, 6, 7, 1
- Check the ones if two numbers have the same tens. The ones decide between them.86, 48, 68, 78, 16
- Choose the greatest. It is the biggest of the numbers in the list.86
Check. Put the others in order to check: 86 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.7, 8, 7
- Check the ones if two numbers have the same tens. The ones decide between them.75, 88, 76
- Choose the least. It is the smallest of the numbers in the list.75
Check. Put the others in order to check: 75 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.6, 9, 2, 4
- Check the ones if two numbers have the same tens. The ones decide between them.65, 90, 24, 44
- Choose the least. It is the smallest of the numbers in the list.24
Check. Put the others in order to check: 24 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.1, 4, 2
- Check the ones if two numbers have the same tens. The ones decide between them.19, 43, 23
- Choose the least. It is the smallest of the numbers in the list.19
Check. Put the others in order to check: 19 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.7, 3, 4, 7, 5
- Check the ones if two numbers have the same tens. The ones decide between them.76, 33, 46, 78, 56
- Choose the greatest. It is the biggest of the numbers in the list.78
Check. Put the others in order to check: 78 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.1, 6, 1
- Check the ones if two numbers have the same tens. The ones decide between them.19, 65, 16
- Choose the greatest. It is the biggest of the numbers in the list.65
Check. Put the others in order to check: 65 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.3, 5, 8, 2
- Check the ones if two numbers have the same tens. The ones decide between them.32, 55, 82, 28
- Choose the least. It is the smallest of the numbers in the list.28
Check. Put the others in order to check: 28 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.3, 4, 8, 2
- Check the ones if two numbers have the same tens. The ones decide between them.32, 44, 86, 28
- Choose the least. It is the smallest of the numbers in the list.28
Check. Put the others in order to check: 28 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
One more, one less, ten more and ten less
To find 1 more, count on one. To find 1 less, count back one.
To find 10 more, the tens digit goes up by one. To find 10 less, the tens digit goes down by one.
Key ideas
- 10 more is one more ten.
- 10 less is one less ten.
- The ones digit stays the same when you add or take away ten.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.47
- Change it. Add ten. The tens digit goes up by one.47 + 10 = 57
- Write the answer. 57
Check. Reverse the change: 57 - 10 gives 47.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.83
- Change it. Take away ten. The tens digit goes down by one.83 - 10 = 73
- Write the answer. 73
Check. Reverse the change: 73 + 10 gives 83.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.59
- Change it. Add one. Count on to the next number.59 + 1 = 60
- Write the answer. 60
Check. Reverse the change: 60 - 1 gives 59.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Watch out
Watch out. 10 more than 47 is 57, not 48. Ten more changes the tens.
Exam tip
Grown-up tip. Use a hundred square. Ask the child to move down one row for 10 more and up one row for 10 less.
Exercise 3D Practice: one more, ten more and less
Non-calculatorMethod. Change the number by the amount in the question.
- Start with the number. It is the number we change.70
- Change it. Take away one. Count back to the number before.70 - 1 = 69
- Write the answer. 69
Check. Reverse the change: 69 + 1 gives 70.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.3
- Change it. Add ten. The tens digit goes up by one.3 + 10 = 13
- Write the answer. 13
Check. Reverse the change: 13 - 10 gives 3.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.76
- Change it. Take away ten. The tens digit goes down by one.76 - 10 = 66
- Write the answer. 66
Check. Reverse the change: 66 + 10 gives 76.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.87
- Change it. Take away ten. The tens digit goes down by one.87 - 10 = 77
- Write the answer. 77
Check. Reverse the change: 77 + 10 gives 87.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.73
- Change it. Add ten. The tens digit goes up by one.73 + 10 = 83
- Write the answer. 83
Check. Reverse the change: 83 - 10 gives 73.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.43
- Change it. Add ten. The tens digit goes up by one.43 + 10 = 53
- Write the answer. 53
Check. Reverse the change: 53 - 10 gives 43.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.79
- Change it. Add ten. The tens digit goes up by one.79 + 10 = 89
- Write the answer. 89
Check. Reverse the change: 89 - 10 gives 79.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.71
- Change it. Take away ten. The tens digit goes down by one.71 - 10 = 61
- Write the answer. 61
Check. Reverse the change: 61 + 10 gives 71.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.20
- Change it. Take away one. Count back to the number before.20 - 1 = 19
- Write the answer. 19
Check. Reverse the change: 19 + 1 gives 20.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.47
- Change it. Add ten. The tens digit goes up by one.47 + 10 = 57
- Write the answer. 57
Check. Reverse the change: 57 - 10 gives 47.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.99
- Change it. Take away one. Count back to the number before.99 - 1 = 98
- Write the answer. 98
Check. Reverse the change: 98 + 1 gives 99.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.17
- Change it. Add one. Count on to the next number.17 + 1 = 18
- Write the answer. 18
Check. Reverse the change: 18 - 1 gives 17.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.39
- Change it. Take away one. Count back to the number before.39 - 1 = 38
- Write the answer. 38
Check. Reverse the change: 38 + 1 gives 39.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.40
- Change it. Add one. Count on to the next number.40 + 1 = 41
- Write the answer. 41
Check. Reverse the change: 41 - 1 gives 40.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.75
- Change it. Add ten. The tens digit goes up by one.75 + 10 = 85
- Write the answer. 85
Check. Reverse the change: 85 - 10 gives 75.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.50
- Change it. Take away one. Count back to the number before.50 - 1 = 49
- Write the answer. 49
Check. Reverse the change: 49 + 1 gives 50.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Numbers between two others
A number between two numbers comes after the smaller one and before the bigger one.
On a number line, count along from the smaller number to see which numbers are between.
Key ideas
- Between means after the smaller number and before the bigger one.
- The two end numbers are not between.
- Halfway means the same distance from both ends.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 34. The smaller number is where we start.34
- Count on until just before 39. Numbers between come after the smaller one and before the bigger one.35, 36, 37, 38
- Write one of the numbers. Any of these is correct.Accept any of 35, 36, 37, 38
Check. Check: any number from the list is bigger than 34 and smaller than 39.
Watch out. Do not write 34 or 39. They are the ends, not the numbers between.
Method. Halfway is the number in the middle when we count along the line.
- Start at 40. It is one end of the line.40
- Count on in ones to the middle. Five steps from 40 reaches the middle.41, 42, 43, 44, 45
- Write the answer. It is the same distance from both ends.45
Check. 45 is 5 more than 40, and 5 less than 50.
Watch out. Halfway means the same number of steps from both ends.
Method. Halfway is the number in the middle when we count along the line.
- Start at 70. It is one end of the line.70
- Count on in ones to the middle. Five steps from 70 reaches the middle.71, 72, 73, 74, 75
- Write the answer. It is the same distance from both ends.75
Check. 75 is 5 more than 70, and 5 less than 80.
Watch out. Halfway means the same number of steps from both ends.
Watch out
Watch out. When you write a number between 34 and 39, do not write 34 or 39. Those are the ends.
Exam tip
Grown-up tip. Draw a long number line on paper with the two numbers at the ends. Ask: “Which numbers fit in the middle?”
Exercise 3E Practice: numbers between
Non-calculatorMethod. Halfway is the number in the middle when we count along the line.
- Start at 30. It is one end of the line.30
- Count on in ones to the middle. Five steps from 30 reaches the middle.31, 32, 33, 34, 35
- Write the answer. It is the same distance from both ends.35
Check. 35 is 5 more than 30, and 5 less than 40.
Watch out. Halfway means the same number of steps from both ends.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 28. The smaller number is where we start.28
- Count on until just before 32. Numbers between come after the smaller one and before the bigger one.29, 30, 31
- Write one of the numbers. Any of these is correct.Accept any of 29, 30, 31
Check. Check: any number from the list is bigger than 28 and smaller than 32.
Watch out. Do not write 28 or 32. They are the ends, not the numbers between.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 45. The smaller number is where we start.45
- Count on until just before 50. Numbers between come after the smaller one and before the bigger one.46, 47, 48, 49
- Write one of the numbers. Any of these is correct.Accept any of 46, 47, 48, 49
Check. Check: any number from the list is bigger than 45 and smaller than 50.
Watch out. Do not write 45 or 50. They are the ends, not the numbers between.
Method. Halfway is the number in the middle when we count along the line.
- Start at 40. It is one end of the line.40
- Count on in ones to the middle. Five steps from 40 reaches the middle.41, 42, 43, 44, 45
- Write the answer. It is the same distance from both ends.45
Check. 45 is 5 more than 40, and 5 less than 50.
Watch out. Halfway means the same number of steps from both ends.
Method. Halfway is the number in the middle when we count along the line.
- Start at 50. It is one end of the line.50
- Count on in ones to the middle. Five steps from 50 reaches the middle.51, 52, 53, 54, 55
- Write the answer. It is the same distance from both ends.55
Check. 55 is 5 more than 50, and 5 less than 60.
Watch out. Halfway means the same number of steps from both ends.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 81. The smaller number is where we start.81
- Count on until just before 84. Numbers between come after the smaller one and before the bigger one.82, 83
- Write one of the numbers. Any of these is correct.Accept any of 82, 83
Check. Check: any number from the list is bigger than 81 and smaller than 84.
Watch out. Do not write 81 or 84. They are the ends, not the numbers between.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 92. The smaller number is where we start.92
- Count on until just before 97. Numbers between come after the smaller one and before the bigger one.93, 94, 95, 96
- Write one of the numbers. Any of these is correct.Accept any of 93, 94, 95, 96
Check. Check: any number from the list is bigger than 92 and smaller than 97.
Watch out. Do not write 92 or 97. They are the ends, not the numbers between.
Method. Halfway is the number in the middle when we count along the line.
- Start at 60. It is one end of the line.60
- Count on in ones to the middle. Five steps from 60 reaches the middle.61, 62, 63, 64, 65
- Write the answer. It is the same distance from both ends.65
Check. 65 is 5 more than 60, and 5 less than 70.
Watch out. Halfway means the same number of steps from both ends.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 22. The smaller number is where we start.22
- Count on until just before 26. Numbers between come after the smaller one and before the bigger one.23, 24, 25
- Write one of the numbers. Any of these is correct.Accept any of 23, 24, 25
Check. Check: any number from the list is bigger than 22 and smaller than 26.
Watch out. Do not write 22 or 26. They are the ends, not the numbers between.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 74. The smaller number is where we start.74
- Count on until just before 78. Numbers between come after the smaller one and before the bigger one.75, 76, 77
- Write one of the numbers. Any of these is correct.Accept any of 75, 76, 77
Check. Check: any number from the list is bigger than 74 and smaller than 78.
Watch out. Do not write 74 or 78. They are the ends, not the numbers between.
Method. Halfway is the number in the middle when we count along the line.
- Start at 20. It is one end of the line.20
- Count on in ones to the middle. Five steps from 20 reaches the middle.21, 22, 23, 24, 25
- Write the answer. It is the same distance from both ends.25
Check. 25 is 5 more than 20, and 5 less than 30.
Watch out. Halfway means the same number of steps from both ends.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 48. The smaller number is where we start.48
- Count on until just before 52. Numbers between come after the smaller one and before the bigger one.49, 50, 51
- Write one of the numbers. Any of these is correct.Accept any of 49, 50, 51
Check. Check: any number from the list is bigger than 48 and smaller than 52.
Watch out. Do not write 48 or 52. They are the ends, not the numbers between.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 30. The smaller number is where we start.30
- Count on until just before 35. Numbers between come after the smaller one and before the bigger one.31, 32, 33, 34
- Write one of the numbers. Any of these is correct.Accept any of 31, 32, 33, 34
Check. Check: any number from the list is bigger than 30 and smaller than 35.
Watch out. Do not write 30 or 35. They are the ends, not the numbers between.
Method. Halfway is the number in the middle when we count along the line.
- Start at 90. It is one end of the line.90
- Count on in ones to the middle. Five steps from 90 reaches the middle.91, 92, 93, 94, 95
- Write the answer. It is the same distance from both ends.95
Check. 95 is 5 more than 90, and 5 less than 100.
Watch out. Halfway means the same number of steps from both ends.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 27. The smaller number is where we start.27
- Count on until just before 30. Numbers between come after the smaller one and before the bigger one.28, 29
- Write one of the numbers. Any of these is correct.Accept any of 28, 29
Check. Check: any number from the list is bigger than 27 and smaller than 30.
Watch out. Do not write 27 or 30. They are the ends, not the numbers between.
Method. Halfway is the number in the middle when we count along the line.
- Start at 10. It is one end of the line.10
- Count on in ones to the middle. Five steps from 10 reaches the middle.11, 12, 13, 14, 15
- Write the answer. It is the same distance from both ends.15
Check. 15 is 5 more than 10, and 5 less than 20.
Watch out. Halfway means the same number of steps from both ends.
Chapter summary
| Skill | Method |
|---|---|
| Compare | Compare tens first, then ones. Use <, > or = |
| Order | Look at the tens, then the ones. Read the list again |
| Greatest and least | The biggest and the smallest, found by comparing tens |
| 10 more and 10 less | Change the tens digit by one. The ones stay the same |
| Between | After the smaller number, before the bigger one |
Can you…?
- I can use <, > and = to compare two numbers
- I can put up to five numbers in order
- I can find the greatest and the least number in a set
- I can find 1 more, 1 less, 10 more and 10 less
- I can find a number between two others
Key terms
- less than
- smaller; the sign is <
- greater than
- bigger; the sign is >
- order
- the way numbers go, smallest to largest or largest to smallest
- between
- after the smaller number and before the bigger number
Exercise 3Z Check-up
Non-calculatorMethod. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.88: 8 tens, 43: 4 tens, 60: 6 tens, 79: 7 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.43
- Write the numbers in order. Check that each one fits between the ones next to it.43, 60, 79, 88
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.9 and 3
- Tens are different, so the tens decide. 9 tens is more than 3 tens.9 tens and 3 tens
- Write the sign. 95 is greater than 34.>
Check. 95 > 34 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.92
- Change it. Take away one. Count back to the number before.92 - 1 = 91
- Write the answer. 91
Check. Reverse the change: 91 + 1 gives 92.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.82: 8 tens, 93: 9 tens, 26: 2 tens, 96: 9 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.26
- Write the numbers in order. Check that each one fits between the ones next to it.26, 82, 93, 96
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.13
- Change it. Take away ten. The tens digit goes down by one.13 - 10 = 3
- Write the answer. 3
Check. Reverse the change: 3 + 10 gives 13.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.73
- Change it. Take away ten. The tens digit goes down by one.73 - 10 = 63
- Write the answer. 63
Check. Reverse the change: 63 + 10 gives 73.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Find the greatest number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.3, 7, 6
- Check the ones if two numbers have the same tens. The ones decide between them.38, 70, 61
- Choose the greatest. It is the biggest of the numbers in the list.70
Check. Put the others in order to check: 70 is the greatest of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Change the number by the amount in the question.
- Start with the number. It is the number we change.58
- Change it. Take away one. Count back to the number before.58 - 1 = 57
- Write the answer. 57
Check. Reverse the change: 57 + 1 gives 58.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.1 and 8
- Tens are different, so the tens decide. 1 tens is fewer than 8 tens.1 tens and 8 tens
- Write the sign. 10 is less than 85.<
Check. 10 < 85 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.93: 9 tens, 67: 6 tens, 60: 6 tens, 11: 1 tens, 96: 9 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.11
- Write the numbers in order. Check that each one fits between the ones next to it.11, 60, 67, 93, 96
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Total 19 marks. Allow about 19 minutes.
Exercise 3X Practice test questions
Non-calculatorMethod. Change the number by the amount in the question.
- Start with the number. It is the number we change.35
- Change it. Take away ten. The tens digit goes down by one.35 - 10 = 25
- Write the answer. 25
Check. Reverse the change: 25 + 10 gives 35.
Watch out. Ten more changes only the tens digit. One more can change the tens too: 1 more than 59 is 60.
Method. Halfway is the number in the middle when we count along the line.
- Start at 70. It is one end of the line.70
- Count on in ones to the middle. Five steps from 70 reaches the middle.71, 72, 73, 74, 75
- Write the answer. It is the same distance from both ends.75
Check. 75 is 5 more than 70, and 5 less than 80.
Watch out. Halfway means the same number of steps from both ends.
Method. Halfway is the number in the middle when we count along the line.
- Start at 30. It is one end of the line.30
- Count on in ones to the middle. Five steps from 30 reaches the middle.31, 32, 33, 34, 35
- Write the answer. It is the same distance from both ends.35
Check. 35 is 5 more than 30, and 5 less than 40.
Watch out. Halfway means the same number of steps from both ends.
Method. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.7, 8, 9
- Check the ones if two numbers have the same tens. The ones decide between them.71, 87, 97
- Choose the least. It is the smallest of the numbers in the list.71
Check. Put the others in order to check: 71 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Count on from the smaller number. Stop just before the bigger one.
- Start at 75. The smaller number is where we start.75
- Count on until just before 79. Numbers between come after the smaller one and before the bigger one.76, 77, 78
- Write one of the numbers. Any of these is correct.Accept any of 76, 77, 78
Check. Check: any number from the list is bigger than 75 and smaller than 79.
Watch out. Do not write 75 or 79. They are the ends, not the numbers between.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.99: 9 tens, 56: 5 tens, 14: 1 tens, 75: 7 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.14
- Write the numbers in order. Check that each one fits between the ones next to it.14, 56, 75, 99
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Find the least number by comparing the tens first.
- Look at the tens. The numbers with the most tens are the greatest.3, 8, 6
- Check the ones if two numbers have the same tens. The ones decide between them.34, 87, 65
- Choose the least. It is the smallest of the numbers in the list.34
Check. Put the others in order to check: 34 is the least of them all.
Watch out. The number with the largest ones digit is not always the greatest.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.9 and 6
- Tens are different, so the tens decide. 9 tens is more than 6 tens.9 tens and 6 tens
- Write the sign. 92 is greater than 62.>
Check. 92 > 62 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.
Method. Put the numbers in order, smallest to largest. Find the first one and then the next.
- Look at the tens of each number. The numbers with fewer tens are smaller.29: 2 tens, 69: 6 tens, 85: 8 tens, 80: 8 tens
- Find the first number in the order. It is the smallest, or the largest if we go the other way.29
- Write the numbers in order. Check that each one fits between the ones next to it.29, 69, 80, 85
Check. Read the list again. Each number is bigger than the one before.
Watch out. Compare tens first. 52 comes before 61 because 5 tens is less than 6 tens.
Method. Compare the tens first. If the tens are the same, compare the ones.
- Compare the tens digits. The tens digit is worth the most.9 and 7
- Tens are different, so the tens decide. 9 tens is more than 7 tens.9 tens and 7 tens
- Write the sign. 99 is greater than 71.>
Check. 99 > 71 is true.
Watch out. Compare tens first. 61 is greater than 58, because 6 tens is more than 5 tens.