(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I need to understand how signed multiplication is done in 2's to 10's complement.

2. Relevant equations

The complement D' of a number D with m digits in base r is r^{m}- D.

So, the complement of 010 in binary (2 in dec) is 1000 - 010 = 110 (-2, but 6 if it were unsigned). We add a leading 0 because there is no such thing as positive 2 in 2-bit 2's complement.

The complement of 20 in ternary (6) is 10 (3) because they sum to 100 (9, or 3^{2}).

3. The attempt at a solution

I understand how multiplication works in binary, but I'm having trouble figuring out how it extend to higher bases. For example, 12 * 22 (5 * -1) in three's complement. I know that it is the complement of 12, which is 11, but I have no idea how to work this out as a multiplication problem. The particular homework problem I'm being asked to solve is 202 * 121 (-7 * -11), but obviously I'm not really looking for an answer here.

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# Homework Help: How do I multiply positive and negative numbers? (in n's complement)

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