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In this worksheet, students work out the missing number in addition sums. They try to do the calculations mentally. Key stage:  KS 3

Curriculum topic:   Number

Curriculum subtopic:   Use Relationships Between Operations

Difficulty level:   ### QUESTION 1 of 10

In this worksheet, you must work out the missing numbers.

Example1

26 + = 50

Here it is easy to work out the inverse.

50 - 26 = 24

Example2

-26 + = 50

Here we use the inverse again, but be careful about the negative sign.

50 - -26 = 50 + 26 = 76

20 + = 55

0.2 + = 1

31 + = 100

0.6 + = 1

-27 + = 100

0.26 + = 1

59 + = 100

0.3 + = 1

0.67 + = 1

-20 + = 50
• Question 1

20 + = 55
35
• Question 2

0.2 + = 1
0.8
• Question 3

31 + = 100
69
• Question 4

0.6 + = 1
0.4
• Question 5

-27 + = 100
127
• Question 6

0.26 + = 1
0.74
• Question 7

59 + = 100
41
• Question 8

0.3 + = 1
0.7
• Question 9

0.67 + = 1
0.33
• Question 10

-20 + = 50
70
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