Page 37 - Maths Class 04

FAST SUBTRACTION 705 – 99 140 – 88

Trick : First subtract a bigger number = 705 – 100 + 1 = 140 – 90 + 2

then add back same to correct the error = 605 + 1 = 606 = 50 + 2 = 52

1. Fill in the table subtracting 99 each time.

n 125 293 346 404 487 510 640 849

n – 99

Strategy : Add up to find the difference of two numbers.

To solve 93 – 28, start + 2 + 30 + 3 + 40 + 200 + 20
at 28 and add until
you reach 93. How 28 30 90 93 160 200 400 420

much you added is the 93 – 28 = (2 + 30 + 3) 420 – 160 = (40 + 200 + 20)

difference. = 35 = 260

2. Use fast subtraction or a helping problem or add up to find the difference or

use other tricks to find the difference of two numbers.

a. 91 – 82 = ______ b. 100 – 82 = ______ c. 56 – 29 = ______

d. 42 – 37 = ______ e. 100 – 56 = ______ f. 161 – 39 = ______

g. 77 – 64 = ______ h. 96 – 48 = ______ i. 84 – 38 = ______

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