Tag Archives: multiplication

Complex multiplication: proof

Posted on October 18, 2016 by Brent

In my previous post, I claimed that when multiplying two complex numbers, their lengths multiply and their angles add, like this: In particular, this means that there are always different complex numbers whose th power is equal to : they … Continue reading →

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Complex multiplication and roots of unity

Posted on October 14, 2016 by Brent

If played around with the question from my previous post, you probably found something like the following: That is, as the powers of we get , , and with all possible sign combinations. Of course, since , if we continue … Continue reading →

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Minus times minus is plus

Posted on September 29, 2009 by Brent

I’ve seen several recent posts wondering about an intuitive explanation for the fact that “a minus times a minus equal to a plus”. I understand why people would wonder about this—the way it’s often taught, it seems to be just … Continue reading →

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Ways to multiply

Posted on June 12, 2009 by Brent

Ξ at 360 has a couple of posts (with more to come!) listing a bunch of different algorithms for performing multiplication. Did you even know there was more than one? Would you be surprised to learn that over the years, … Continue reading →

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