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senary spinoffs
Posted By: Don Thompson
Date: Saturday, 23 January 2010, at 7:32 p.m.
In Response To: senary spinoffs (Nack Ballard)
Yeah , That is a typo in the pattern , thanks for noticing it.
Getting the digits in the right place in the multiplication is just a matter of moving it once to the right for each step. Muliplying top down like this is kind of cumbersome in text, but if you just roll step by step in your head and put the number together as you go it's pretty simple and quick
Doing the same thing in decimal : 42 x 32
we could multiply 4 x 3 for 12
then (4 x 2) + (3 x 2) for 14
then 2 x 2 for 4
when we compile them we have to move the digits like
12
014
0004
so we get 1344The last digit of the step just moves one place to the right of the last step. so the multiplicaton itself doesn't usually cause much trouble. If I do in my head, I always add the numbers together each step and just 'build' the number as I go rather than taking the steps and doing addition at the end but there doesn't seem to be an easy way to describe that on paper without making it more confusing or very long.
Of course there are other tricks that can be used for multiplication, but rolling from the top like that is my default and if I use a polynomial trick or something else I still think of it as top down from the front.
The place where I go wrong on the digits usually comes after I get a number all ground out, not during the multiplication. For example I may have just done a takepoint calculation, and gotten confused and not sure if it's 0:0:1:4 , 0:1:4 or 1:4:0 etc. but those numbers are usually different enough that if you know the context of what you're trying to find only one of them is usually in the ballpark, so it's rarely a problem.
Don Thompson

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