Wednesday, 8 June 2016

Subtraction 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? Because 8 + 10 = 18 and 55-18 makes it the same as the other one.

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
(2) 65 – 19 = 65 – 9 - 10
(3) 46 – 28 = 46 – 8 - 20
4) 41 – 12 = 41 - 6 - … 6

(5) 94 – 25 = 94 – 5 - 20
(6) 62 – 28 = 62 - 20 - …8

7) 36 – 17 = 36 – … 10 - 7

(8) 52 – 25 = 52 - 20 - 5
(9) 63 – 36 = 63 – … 6 - 30

10) 73 – 15 = 73 – 10 - …5

(11) 423 - 17 = 423 - … 10 - 7

(12) 306 – 27 = 306 - 20 - 7