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Originally Posted by danielf
Multiply 39.6 by 50. 50*39.6 = 5* 396 = 5*400 - (5*4) = 2000 - 20 = 1980
Now subtract 0.5 * 39.6 = 19.8
1980 - 19.8 = 1960.2 Easy...  |
Or 39.6 x 100 (move dec point two places right) = 3960, divide by 2 = 1980
similarly 39.6 x 1 = 39.6 / 2 = 19.8
1980 - 19.8 =
1960.2