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You can also use your 10 fingers to instantly multiply by 9s. Spread out your fingers. Number them from 1 to 10, left to right (i.e. left-hand little finger =
by qubitcoder 11y ago
You can also use your 10 fingers to instantly multiply by 9s.
Spread out your fingers. Number them from 1 to 10, left to right (i.e. left-hand little finger = 1).
For 9 * 7, simply curl finger 7 downwards.
Now you have 6 fingers on the left, and 3 fingers on the right. Voila, 63. :-)