 # Addition and Subtraction Facts to 100 (1)

In this worksheet, students must know by heart their addition and subtraction number bonds to 20 and use them to derive related facts to 100. Key stage:  KS 1

Curriculum topic:   Number: Addition and Subtraction

Curriculum subtopic:   Use Addition/Subtraction Facts to 100

Difficulty level:   ### QUESTION 1 of 10

Look at this number square, which shows all the bonds you should know by heart up to 20. You can use this table to work out additions and subtractions right up to 100.

Example 1

We split 36 into 30 and 6.

We now need to work out

30 + 6 + 9

You should know this by heart, but the number square shows that

6 + 9 = 15 So

36 + 9   = 30 + 6 + 9

= 30 + 15 = 45

Example 2

Subtract  25 - 9

We split 25 into 10 and 15.

We now need to work out

10 + 15 - 9

You should know this by heart, but the number square shows that

15 - 9 = 6

When you subtract, the starting number is inside the square. So

25 - 9  = 10 + 15 - 9

= 10 + 6 = 16

56 + 8

Subtract

24 - 7

36 + 10

Subtract

24 - 6

23 + 8

Subtract

24 - 5

35 + 8

Subtract

34 - 3

56 + 2

Subtract

22 - 8

• Question 1

56 + 8

64
EDDIE SAYS
50 + 6 + 8 = 50 + 14
• Question 2

Subtract

24 - 7

17
EDDIE SAYS
10 + 14 - 7 = 10 + 7
• Question 3

36 + 10

46
EDDIE SAYS
30 + 6 + 10 = 30 + 16 or 30 + 10 + 6
• Question 4

Subtract

24 - 6

18
EDDIE SAYS
10 + 14 - 6 = 10 + 8
• Question 5

23 + 8

31
EDDIE SAYS
20 + 3 + 8 = 20 + 11
• Question 6

Subtract

24 - 5

19
EDDIE SAYS
10 + 14 - 5 = 10 + 9
• Question 7

35 + 8

43
EDDIE SAYS
30 + 5 + 8 = 30 + 13
• Question 8

Subtract

34 - 3

31
EDDIE SAYS
20 + 14 - 3 = 20 + 11 or count back 3
• Question 9

56 + 2

58
EDDIE SAYS
50 + 6 + 2 = 50 + 8
• Question 10

Subtract

22 - 8

14
EDDIE SAYS
10 + 12 - 8 = 10 + 4
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