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Posted: Feb 05 2007 01:54 am

My girlfriend came upon this and I find this to be awesome as I'm highly fond of mathematics. I've never heard of this before, so if this is common knowledge, I apologize.

I don't know if it works all the time or only with certain numbers. I'm going to test it now.

Posted: Feb 05 2007 02:28 am

I tested it multiplying up to two five-digit numbers, so I think it's a solid method. This is neato.

Posted: Feb 05 2007 02:56 am

Yeah, it's mathematically sound. If you multiply m x n, there will be m + n - 1 'sections' to count. The numbers in those sections are going to be the numbers that have the same first digit log10.

In the second example, 1x1, 2x2, and 3x3, all get added in the middle section because 100x1, 20x20, and 3x300 all have a log10 of 2 (floored).

EDIT: Sorry, I worded that wrong. The log of the individual numbers (floored) will sum to be the same in each section.
(i.e. log 100 = 2, log 1 = 0, 2 + 0 = 2)

Posted: Feb 05 2007 11:58 am

Neat! It's like a calculator on paper, much easier to do than a bunch of bullshit in your head.

Also, that guy writes 9's like lowercase g's.

Posted: Feb 05 2007 03:20 pm

Murdar Machene wrote:

Neat! It's like a calculator on paper, much easier to do than a bunch of bullshit in your head.

Also, that guy writes 9's like lowercase g's.

Yea. That really bothered me.

Posted: Feb 05 2007 04:47 pm

I like calculators... but if I ever end up on a deserted island and get so bored I feel the need to multipy coconuts, I'll draw lines in the sand.

Thanks guys!