Step-by-step Maths Level 3: Missing numbers and dividing with 2, 5 and 10
Part of the Step-by-step Maths Level 3 multiplying with 2, 5 and 10 chapter. Chapter overview · whole chapter on one page
Missing numbers and dividing with 2, 5 and 10
Division is the opposite of multiplication. 30 ÷ 5 asks: how many groups of 5 make 30?
Use the same facts to find a missing number. 5 × ___ = 35 asks: what times 5 makes 35?
Key ideas
- Division asks how many groups.
- The inverse of × is ÷.
- Count in steps to find the missing number.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think: how many groups of 5 make 35? Count in steps of the first number.5, 10, 15, 20, 25, 30, 35
- Count the groups. We said 7 numbers, so there are 7 groups.7 groups of 5
- Write the missing number. This is the number of groups.7
Check. Check: 5 × 7 = 35.
Watch out. The times table of 5 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 10 × ? = 60. Division asks how many groups.10 × ? = 60
- Count in 10s until you reach 60. Count the steps as you go.10, 20, 30, 40, 50, 60
- Write the answer. This is the number of groups.6
Check. Check: 10 × 6 = 60, so 60 ÷ 10 = 6.
Watch out. The times table of 10 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Count in 2s until you reach 10. Each count is one group.2, 4, 6, 8, 10
- Count the numbers you said. There are 5 numbers, so there are 5 groups.5 groups
- Write the answer. This is the number of groups.5
Check. Check: 2 × 5 = 10.
Watch out. The times table of 2 is the key. Division is the opposite of multiplication.
Watch out
Watch out. 30 ÷ 5 is 6, because 5 × 6 = 30. Do not divide 5 by 30.
Exam tip
Grown-up tip. Ask: “What times the number makes this answer? Count in steps until you get there.”
Exercise 7D Practice: missing numbers and division
Non-calculatorMethod. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 5 × ? = 60. Division asks how many groups.5 × ? = 60
- Count in 5s until you reach 60. Count the steps as you go.5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60
- Write the answer. This is the number of groups.12
Check. Check: 5 × 12 = 60, so 60 ÷ 5 = 12.
Watch out. The times table of 5 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 2 × ? = 4. Division asks how many groups.2 × ? = 4
- Count in 2s until you reach 4. Count the steps as you go.2, 4
- Write the answer. This is the number of groups.2
Check. Check: 2 × 2 = 4, so 4 ÷ 2 = 2.
Watch out. The times table of 2 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Count in 2s until you reach 16. Each count is one group.2, 4, 6, 8, 10, 12, 14, 16
- Count the numbers you said. There are 8 numbers, so there are 8 groups.8 groups
- Write the answer. This is the number of groups.8
Check. Check: 2 × 8 = 16.
Watch out. The times table of 2 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 2 × ? = 6. Division asks how many groups.2 × ? = 6
- Count in 2s until you reach 6. Count the steps as you go.2, 4, 6
- Write the answer. This is the number of groups.3
Check. Check: 2 × 3 = 6, so 6 ÷ 2 = 3.
Watch out. The times table of 2 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Count in 5s until you reach 40. Each count is one group.5, 10, 15, 20, 25, 30, 35, 40
- Count the numbers you said. There are 8 numbers, so there are 8 groups.8 groups
- Write the answer. This is the number of groups.8
Check. Check: 5 × 8 = 40.
Watch out. The times table of 5 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 2 × ? = 14. Division asks how many groups.2 × ? = 14
- Count in 2s until you reach 14. Count the steps as you go.2, 4, 6, 8, 10, 12, 14
- Write the answer. This is the number of groups.7
Check. Check: 2 × 7 = 14, so 14 ÷ 2 = 7.
Watch out. The times table of 2 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think: how many groups of 5 make 10? Count in steps of the first number.5, 10
- Count the groups. We said 2 numbers, so there are 2 groups.2 groups of 5
- Write the missing number. This is the number of groups.2
Check. Check: 5 × 2 = 10.
Watch out. The times table of 5 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 5 × ? = 55. Division asks how many groups.5 × ? = 55
- Count in 5s until you reach 55. Count the steps as you go.5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55
- Write the answer. This is the number of groups.11
Check. Check: 5 × 11 = 55, so 55 ÷ 5 = 11.
Watch out. The times table of 5 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Count in 5s until you reach 35. Each count is one group.5, 10, 15, 20, 25, 30, 35
- Count the numbers you said. There are 7 numbers, so there are 7 groups.7 groups
- Write the answer. This is the number of groups.7
Check. Check: 5 × 7 = 35.
Watch out. The times table of 5 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 10 × ? = 110. Division asks how many groups.10 × ? = 110
- Count in 10s until you reach 110. Count the steps as you go.10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110
- Write the answer. This is the number of groups.11
Check. Check: 10 × 11 = 110, so 110 ÷ 10 = 11.
Watch out. The times table of 10 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 2 × ? = 22. Division asks how many groups.2 × ? = 22
- Count in 2s until you reach 22. Count the steps as you go.2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22
- Write the answer. This is the number of groups.11
Check. Check: 2 × 11 = 22, so 22 ÷ 2 = 11.
Watch out. The times table of 2 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 10 × ? = 40. Division asks how many groups.10 × ? = 40
- Count in 10s until you reach 40. Count the steps as you go.10, 20, 30, 40
- Write the answer. This is the number of groups.4
Check. Check: 10 × 4 = 40, so 40 ÷ 10 = 4.
Watch out. The times table of 10 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 10 × ? = 70. Division asks how many groups.10 × ? = 70
- Count in 10s until you reach 70. Count the steps as you go.10, 20, 30, 40, 50, 60, 70
- Write the answer. This is the number of groups.7
Check. Check: 10 × 7 = 70, so 70 ÷ 10 = 7.
Watch out. The times table of 10 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Think of the multiplication: 10 × ? = 50. Division asks how many groups.10 × ? = 50
- Count in 10s until you reach 50. Count the steps as you go.10, 20, 30, 40, 50
- Write the answer. This is the number of groups.5
Check. Check: 10 × 5 = 50, so 50 ÷ 10 = 5.
Watch out. The times table of 10 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Count in 2s until you reach 10. Each count is one group.2, 4, 6, 8, 10
- Count the numbers you said. There are 5 numbers, so there are 5 groups.5 groups
- Write the answer. This is the number of groups.5
Check. Check: 2 × 5 = 10.
Watch out. The times table of 2 is the key. Division is the opposite of multiplication.
Method. Use the 2, 5 or 10 facts. Count in steps of the number to find the missing number.
- Count in 10s until you reach 20. Each count is one group.10, 20
- Count the numbers you said. There are 2 numbers, so there are 2 groups.2 groups
- Write the answer. This is the number of groups.2
Check. Check: 10 × 2 = 20.
Watch out. The times table of 10 is the key. Division is the opposite of multiplication.