*This quiz addresses the requirements of the National Curriculum KS1 Maths and Numeracy for children aged 6 and 7 in year 2. Specifically this quiz is aimed at the section dealing with counting on from any given number. *

Recognising that addition is the inverse, or opposite, of subtraction is useful when it comes to checking answers. For example, realising that 13 - 8 = 5 could be checked by adding 8 + 5 to give 13 means that subtraction calculation answers can be accurately checked.

Question 1

Which calculation could you use to check that 23 - 6 = 17 is correct?

6 + 17

23 + 7

23 + 6 + 7

23 + 6 + 7

If adding the two smaller numbers does not give the larger number as their total, something has gone wrong!

Question 2

Check 67 - 25 = 42 with addition. Is this calculation correct?

Incorrect answer: 25 + 67 = 92

Correct answer: 25 - 67 = 42

Incorrect answer: 67 + 42 = 109

Correct answer: 25 + 42 = 67

The two smaller numbers add to give 67

Question 3

Why is 33 - 20 = 13 true?

Because the sum of all three numbers gives the same answer

Because 13 subtracted from 20 is 33

Because the total of 13 and 33 is 20

Because 20 + 13 = 33

If you had 33 pennies and took 20 away (leaving 13), putting them all back again (13 + 20) would result in 33 pennies again

Question 4

Which calculation proves this calculation is incorrect?

76 - 34 = 45

76 - 34 = 45

76 - 45 = 34

45 - 34 = 11

34 + 45 = 79

34 + 45 = 76

The two smaller numbers do not add to total the larger one

Question 5

Which calculation proves this calculation is incorrect?

62 - 19 = 55

62 - 19 = 55

55 + 19 = 62

55 + 19 = 74

62 + 19 = 55

62 + 55 = 19

The two smaller numbers do not add to total the larger one

Question 6

Which calculation could you use to check that 18 - 7 = 11 is correct?

11 + 18

7 + 18

7 + 11

11 + 7 + 18

Adding the two smaller numbers should total the larger number

Question 7

Which calculation shows that this subtraction is correct?

78 - 40 = 38

78 - 40 = 38

40 + 78 = 38

40 - 38 = 78

38 + 78 = 40

38 + 10 + 10 + 10 + 10 = 78

Adding 4 groups of 10 to 38 gives the starting number of 78

Question 8

How could you check that 24 - 8 = 16?

By checking that 16 + 8 = 24

By checking the total of all three numbers

By finding the difference between 16 and 8

By finding the total of 24 and 8

Adding the two smaller numbers should give the larger one

Question 9

Check 84 - 21 = 73 with addition. Is this calculation correct?

Correct answer: 73 + 21 = 84

Incorrect answer: 73 + 21 = 94

Incorrect answer: 84 + 21 = 105

Incorrect answer: 84 + 73 = 157

The two smaller numbers do not add to give the larger number, so the original calculation is incorrect

Question 10

Why is 48 - 20 = 54 incorrect?

Because 48 is more than 20

Because the numbers are all even

Because 20 + 54 = 74, not 48

Because the total of all three numbers is 122

The answer to a subtraction cannot be larger than the number at the beginning!