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LostInParadise's avatar

How many people would it take to mentally multiply 2 three digit numbers?

Asked by LostInParadise (25106points) June 16th, 2009

Okay, this is kind of a silly exercise, but I think it would be fun to try out to see if it works. It might make a good project for an elementary school class. I say that 5 ordinary (or perhaps mildly deranged) people could collectively mentally multiply 2 three digit numbers.

First of all you have to recall what it was like to multiply numbers on paper. You formed 3 rows by multiplying the top number by each digit of the bottom number and then added them together.

Here is how it would work. One person acts as the multiplier. He would announce in turn each digit of the first row, which another person would be responsible for memorizing. The other two rows would be assigned to two other people. To add the three rows, the multiplier points to each of three row people who will sequentially tell the last digit of their row. The mulitplier adds these numbers, keeps track of the carry and announces the last digit of the product, which would be kept track of by the fifth person. Then the multiplier points in turn to each of the row people, who tell the second to last digit of their number, which the multiplier adds together, combines with the carry and announces to the person keeping track of the product. And so on.

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