*This Math quiz is called 'Addition and Subtraction Facts to 20' and it has been written by teachers to help you if you are studying the subject at elementary school. Playing educational quizzes is a fun way to learn if you are in the 1st or 2nd grade - aged 6 to 8.*

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Knowing addition and subtraction facts (or number facts) to 20 by heart means being able to quickly know the pairs of numbers which make a total of twenty, as well as the associated subtraction facts. For example, if you know that 13 + 7 = 20, then you should also recognize that 20 - 13 = 7 or 20 - 7 = 13.

How well do you know the number facts to 20?

1.

Which of the following is true?

12 - 20 = 8

20 - 2 = 18

8 + 20 = 12

18 + 20 = 2

20 - 18 = 2 is the other subtraction fact for these numbers

2.

Which number fact is incorrect?

11 + 9 = 20

9 + 11 = 20

20 - 9 = 11

11 - 20 = 9

11 - 20 gives a negative answer of -9!

3.

Which number is missing: 17 + ? = 20

5

3

7

9

17 + 3 = 20 and so 3 + 17 = 20 also

4.

Which 'family' of facts is incorrect?

2 + 18 = 20

18 + 2 = 20

20 - 18 = 2

20 - 2 = 18

18 + 2 = 20

20 - 18 = 2

20 - 2 = 18

16 + 5 = 20

5 + 16 = 20

20 - 16 = 5

20 - 5 = 16

5 + 16 = 20

20 - 16 = 5

20 - 5 = 16

5 + 15 = 20

15 + 5 = 20

20 - 5 = 15

20 - 15 = 5

15 + 5 = 20

20 - 5 = 15

20 - 15 = 5

10 + 10 = 20

20 - 10 = 10

20 - 10 = 10

16 + 5 = 21, not 20 so all the other facts must be incorrect too

5.

Which of the following is true?

2 + 18 = 20 so 20 + 18 = 2

2 + 18 = 20 so 18 + 2 = 20

2 + 18 = 20 so 20 + 2 = 18

2 + 18 = 20 so 18 + 20 = 2

Adding the two smaller numbers in any order gives the larger number

6.

Which of the following pairs of number do not add up to give 20?

9 + 11

2 + 18

16 + 5

20 + 0

16 + 5 = 21

7.

If you know that 14 + 6 = 20, what else do you know?

20 + 14 = 6

20 - 14 = 6

14 - 20 = 6

6 - 14 = 20

You would also know that 20 - 6 = 14

8.

Which 'family' of facts is incorrect?

7 + 13 = 20

13 + 7 = 20

20 - 13 = 7

20 - 7 = 13

13 + 7 = 20

20 - 13 = 7

20 - 7 = 13

8 + 12 = 20

12 + 8 = 20

20 - 8 = 12

20 - 12 = 8

12 + 8 = 20

20 - 8 = 12

20 - 12 = 8

9 + 11 = 20

11 + 9 = 20

20 - 11 = 9

20 - 9 = 11

11 + 9 = 20

20 - 11 = 9

20 - 9 = 11

4 + 14 = 20

14 + 4 = 20

20 - 4 = 14

20 - 14 = 4

14 + 4 = 20

20 - 4 = 14

20 - 14 = 4

14 + 4 = 18, so all the other facts must be incorrect too

9.

Which three other facts go with 16 + 4 = 20?

20 + 16 = 4

20 + 4 = 16

16 - 20 = 4

20 + 4 = 16

16 - 20 = 4

16 - 20 = 4

4 - 20 = 16

20 + 16 = 4

4 - 20 = 16

20 + 16 = 4

4 + 16 = 20

16 - 4 = 20

4 - 16 = 20

16 - 4 = 20

4 - 16 = 20

4 + 16 = 20

20 - 16 = 4

20 - 4 = 16

20 - 16 = 4

20 - 4 = 16

For the subtraction facts, the largest number should be at the beginning

10.

Which three pairs of numbers all add up to 20?

19 + 1

17 + 3

5 + 15

17 + 3

5 + 15

12 + 9

11 + 7

3 + 16

11 + 7

3 + 16

7 + 20

6 + 12

7 + 19

6 + 12

7 + 19

4 + 12

16 + 8

20 + 1

16 + 8

20 + 1

All the others add up to different numbers

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