Calculator Puzzles, Tricks and Games by Norvin Pallas

Author:Norvin Pallas [Pallas, Norvin]
Language: eng
Format: epub
ISBN: 9780486157320
Publisher: Dover Publications
Published: 2012-10-11T00:00:00+00:00

There is a fascinating traditional system for multiplying, called Peasant Multiplication, which requires only the ability to halve and double, rather than memorizing complicated multiplication tables.

Peasant Multiplication is a system which is easy to work but hard to explain. Let us suppose that you want to multiply 39 × 71. But you do not know the multiplication tables beyond the 2’s, and you certainly don’t want to go through a long addition problem. Instead, you head two columns with 39 and 71. In the first column you continually divide by 2, ignoring any remainders, and in the second column you constantly double the preceding figure. You check off the odd numbers in the first column, pick up the figure in the second column, and enter it in the third column. The total of the third column is your answer.

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