10 + 90, 20 + 80, 30 + 70, 40 + 60 and 50 + 50 all add up to 100.

# Addition and Subtraction Facts to 100

This Math quiz is called 'Addition and Subtraction Facts to 100' 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 by heart means being able to quickly know the pairs of numbers which make a total of 100, as well as the associated subtraction facts. This knowledge of the number pairs, or bonds, to 100 can be linked to knowing the number pairs to 10. For example, if you know that 3 + 7 = 10, then you may realize that 30 + 70 = 100.

How well do you know the number facts to 100?

1.
Which of the following is true?
10 - 80 = 20
100 - 20 = 80
80 - 20 = 100
20 - 80 = 100
100 - 80 = 20 is the other subtraction fact for these numbers
2.
Which three pairs of numbers all add up to 100?
20 + 80
10 + 90
50 + 50
10 + 80
20 + 18
60 + 4
12 + 18
20 + 8
100 + 10
40 + 6
50 + 5
10 + 9
All the others give different totals
3.
Which of these three other facts go with 30 + 70 = 100?
100 + 30 = 70
70 - 30 = 100
30 - 70 = 100
30 + 30 = 70
70 - 30 = 100
30 - 100 = 70
70 + 70 = 100
30 +30 = 100
100 - 100 = 30
70 + 30 = 100
100 - 30 = 70
100 - 70 = 30
For the subtraction facts, the largest number should be at the beginning
4.
Which 'family' of facts is incorrect?
35 + 65 = 100
65 + 35 = 100
100 - 35 = 65
100 - 65 = 35
25 + 75 = 100
75 + 25 = 100
100 - 25 = 75
100 - 75 = 25
15 + 85 = 100
85 + 15 = 100
100 - 85 = 15
100 - 15 = 85
65 + 45 = 100
45 + 65 = 100
100 - 65 = 45
100 - 45 = 65
65 + 45 = 110, so all the other facts must be incorrect too
5.
Which number fact is incorrect?
6 + 40 = 100
60 + 40 = 100
40 + 60 = 100
100 - 60 = 40
6 + 40 = 46!
6.
Which of the following is true?
6 + 4 = 10, so 60 + 4 = 100
6 + 4 = 10, so 60 + 40 = 100
6 + 4 = 10, so 16 + 14 = 100
6 + 4 = 10, so 6 + 40 = 100
60 + 40 gives an answer which is ten times bigger than 6 + 4
7.
Which 'family' of facts is incorrect?
10 + 90 = 100
90 + 10 = 100
100 - 90 = 10
100 - 10 = 90
20 + 80 = 100
80 + 20 = 100
100 - 20 = 80
100 - 80 = 20
60 + 50 = 100
50 + 60 = 100
100 - 60 = 50
100 - 50 = 60
30 + 70 = 100
70 + 30 = 100
100 - 30 = 70
100 - 70 = 30
60 + 50 = 110, so all the other facts must be incorrect too
8.
Which one of the following number pairs do not add up to give 100?
100 + 0
90 + 10
60 + 40
20 + 18
20 + 18 = 38
9.
If you know that 2 + 8 = 10, what else do you know?
20 + 80 = 100
12 + 18 = 20
2 + 80 = 100
8 + 20 = 100
80 + 20 would also give 100
10.
Which number is missing: 10 + ? = 100
100
9
90
10
10 + 90 = 100, so 90 + 10 = 100 also
Author:  Angela Smith