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Maths Quiz - Year 2 Calculation - Inverse Operations (Questions)

Use inverse operations to check answers. Switch between addition and subtraction to spot mistakes and build confident mental methods.

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Fascinating Fact:

Check addition with subtraction: 28 + 6 = 34? Try 34 − 28. It is 6, so the sum is correct.

In KS1 Maths, Year 2 pupils learn to use inverse operations to check their work. If you add to get an answer, you can subtract to see if you return to the start number.

Key Terms

Inverse: An opposite operation that undoes a calculation, like addition and subtraction.
Fact family: A set of linked addition and subtraction facts that use the same numbers.
Check: A quick test using the inverse to confirm your answer makes sense.

Warm up with quick number checks: try the Numeracy Game before you start the quiz.

Frequently Asked Questions (Click to see answers)

What are inverse operations in Year 2?

Inverse operations are opposite operations that undo each other. In Year 2, we use addition with subtraction to check answers quickly.

How do I check an addition using the inverse?

Take the total and subtract one of the addends. If the result is the other addend, your addition is correct. Example: 19 + 4 = 23, check 23 − 19 = 4.

What is a simple fact family example?

For the numbers 7, 5, and 12: 7 + 5 = 12, 5 + 7 = 12, 12 − 7 = 5, 12 − 5 = 7. These four facts belong together.

Try These Related Quizzes

1.

Which calculation could you use to check that 16 - 9 = 7 is correct?

[ ]	16 + 9 = 7
[ ]	9 + 7 = 16
[ ]	7 - 16 = 9
[ ]	7 - 9 = 16

2.

Which calculation could you use to check that 15 + 8 = 23 is correct?

[ ]	23 + 8 = 15
[ ]	23 + 15 = 8
[ ]	15 - 8 = 23
[ ]	23 - 8 = 15

3.

How do you know that 20 - 10 = 10?

[ ]	Because I know 10 + 10 = 20
[ ]	Because it's a subtraction
[ ]	Because it's an addition
[ ]	Because I know about subtraction

4.

Use number pairs, or bonds, to 20 to find the incorrect calculation:

[ ]	20 - 13 = 7
[ ]	20 - 8 = 12
[ ]	20 - 16 = 14
[ ]	20 - 2 = 18

5.

Use number pairs, or bonds, to 20 to find the incorrect calculation:

[ ]	20 - 10 = 20
[ ]	20 - 0 = 20
[ ]	20 - 15 = 5
[ ]	20 - 19 = 1

6.

If 3 + 4 + 10 + 3 = 20, what could you do to check the answer?

[ ]	Take out all the larger numbers
[ ]	Use multiplication
[ ]	Add some extra numbers in too
[ ]	Add the numbers up again in a different order: 10 + 3 + 3 + 4 or 10 + 4 + 3 + 3

7.

If 29 - 15 = 14, what could you do to check the answer?

[ ]	Subtract the numbers in a different order
[ ]	Add 15 and 14 together
[ ]	Take out any harder numbers
[ ]	Put 14 at the beginning of the calculation

8.

How would you check 45 - 23 = 22?

[ ]	By subtracting 22 from 23
[ ]	By adding 45 and 22
[ ]	By finding the total of all the numbers
[ ]	By adding 23 and 22

9.

How could you check 62 + 38 = 100?

[ ]	By taking away 100
[ ]	By finding the difference between 62 and 38
[ ]	By subtracting 100 from 62
[ ]	By subtracting 38 from 100

10.

What does 'inverse operation' mean?

[ ]	Doing the calculation upside down
[ ]	Making a mistake on purpose
[ ]	The opposite operation
[ ]	A medical procedure

Maths Quiz - Year 2 Calculation - Inverse Operations (Answers)

1.

Which calculation could you use to check that 16 - 9 = 7 is correct?

[ ]	16 + 9 = 7
[x]	9 + 7 = 16
[ ]	7 - 16 = 9
[ ]	7 - 9 = 16

If 9 subtracted from 16 leaves 7, then by adding the 9 back again, you should be back to where you started

2.

Which calculation could you use to check that 15 + 8 = 23 is correct?

[ ]	23 + 8 = 15
[ ]	23 + 15 = 8
[ ]	15 - 8 = 23
[x]	23 - 8 = 15

If a group of 15 and a group of 8 are combined, taking one group away again should leave you with the other

3.

How do you know that 20 - 10 = 10?

[x]	Because I know 10 + 10 = 20
[ ]	Because it's a subtraction
[ ]	Because it's an addition
[ ]	Because I know about subtraction

Using an addition fact can help to solve a subtraction

4.

Use number pairs, or bonds, to 20 to find the incorrect calculation:

[ ]	20 - 13 = 7
[ ]	20 - 8 = 12
[x]	20 - 16 = 14
[ ]	20 - 2 = 18

16 + 14 gives a total of 30, not 20

5.

Use number pairs, or bonds, to 20 to find the incorrect calculation:

[x]	20 - 10 = 20
[ ]	20 - 0 = 20
[ ]	20 - 15 = 5
[ ]	20 - 19 = 1

20 + 10 would not give a total of 20

6.

If 3 + 4 + 10 + 3 = 20, what could you do to check the answer?

[ ]	Take out all the larger numbers
[ ]	Use multiplication
[ ]	Add some extra numbers in too
[x]	Add the numbers up again in a different order: 10 + 3 + 3 + 4 or 10 + 4 + 3 + 3

Addition can be done in any order

7.

If 29 - 15 = 14, what could you do to check the answer?

[ ]	Subtract the numbers in a different order
[x]	Add 15 and 14 together
[ ]	Take out any harder numbers
[ ]	Put 14 at the beginning of the calculation

You can use addition to check a subtraction

8.

How would you check 45 - 23 = 22?

[ ]	By subtracting 22 from 23
[ ]	By adding 45 and 22
[ ]	By finding the total of all the numbers
[x]	By adding 23 and 22

Adding the two smaller numbers should give the larger number

9.

How could you check 62 + 38 = 100?

[ ]	By taking away 100
[ ]	By finding the difference between 62 and 38
[ ]	By subtracting 100 from 62
[x]	By subtracting 38 from 100

If 62 + 38 = 100 is correct, then 100 - 38 should give an answer of 62

10.

What does 'inverse operation' mean?

[ ]	Doing the calculation upside down
[ ]	Making a mistake on purpose
[x]	The opposite operation
[ ]	A medical procedure

The inverse of subtraction is addition, the inverse of addition is subtraction