Subtracting in parts

Subtraction in Parts

LI:We are learning to subtract by splitting numbers into parts instead of counting down.

Exercise 1

Meera looked at 55 – 18 and said this is the same as 55 – 10 - 8 even though she did not work out the answer. How did she know?

For each of the following problems circle true or false.

1) 41 – 15 is the same as 41 – 10 – 5                   T F

2) 68 – 29 is the same as 68 – 20 – 8                   T F

3) 73 – 15 is the same as 73 – 5 – 20                   T F

4) 85 – 19 is the same as 85 – 11 – 8                    T F

5) 43 – 29 is the same as 43 – 20 – 3                     T F

6) 44 – 15 is the same as 44 – 5 – 10                     T F

7) 58 – 19 is the same as 58 -12 – 7                       T F

8) 36 – 17 is the same as 36 – 7 – 10                     T F

Exercise 2

For each of the following fill in the box or circle.

1) 55 – 18 = 55 – 10 - 8=37

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(2) 65 – 19 = 65 – 9 -10=46

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(3) 46 – 28 = 46 – 8 -20=18

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4) 41 – 12 = 41 - 6 -6=29 …

(5) 94 – 25 = 94 – …20 - 5=69

(6) 62 – 28 = 62 - 20 - 8=14…

7) 36 – 17 = 36 – 7… - 10=19

(8) 52 – 25 = 52 - 20 -5=27

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(9) 63 – 36 = 63 – …30 - 6=27

10) 73 – 15 = 73 – 10 - …5=58

(11) 423 - 17 = 423 - …10-7=406

(12) 306 – 27 = 306 -20-7=279