multiplying on fingers also work with bases other than ten, why
At school I was shown how to multiply two intergers, both > 5 and <11 using the fingers on both hands.
Each hand used to represent one of the two numbers.
It works like this e.g 7x8= 56.
On the left hand count from 6 to 7 by folding down two fingers so that two are bend and three are not.
Then on the right hand count from 6 to 8 so that three are bend and two are not.
Count the number of straight fingers on each hand 3x2=6. this represents 6 units.
Count number of bent fingers on both hands and this represent the number of tens, five tens, or fifty.
So the answer is fifty plus six
The question is:
How come this works if we didnt have ten fingers and we counted for example in base 8 and had 8 fingers? If we counted in base 8 we would have 4 fingers on each hand and could multipy numbers from 5 to 8 using this method.