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The Towers of Hanoi and Adventures in Mathematics
(page 1110(2))


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What About Other Bases
It turns out that, although computers use binary numbers, the strings of 0s and 1s are too difficult or awkward for humans to use. Most of the time we just use decimal numbers and let the computer convert them to binary numbers.

But decimal numbers are not good when you want to interpret the computer numbers that may represent things other than numbers, such as characters.

For such numbers computer programmers will often use octal (base 8) of hexadecimal (base 16) numbers. To see these numbers in use, let's look at the representations of the letter 'k':

Letter Binary Octal Decimal Hexadecimal
k 1101011 153 107 6B

Note that the `B' in the hexadecimal number stands for 11 decimal. `A' is used for 10, and 'F' for 15.

And the Ultimate Answer is 42.
If you have heard, read, or seen The Hitch Hiker's Guide to the Galaxy you might remember that the ultimate answer to everything is 42.

Unfortunately the computer that gave the answer was not able to give the question, so the white mice ordered the building of a new supercomputer to figure out the question. That computer turned out to be the earth, but unfortunately the earth was blown up before it could produce the question.

But the H2G2 hero Arthur Dent is accidentally sent back into Earth's past and there he figures out that the question is actually:

What's six times nine?
Given that Arthur thinks in decimal numbers, he does not understand how 6×9, which he thinks is 54, could be 42.

But what if the 42 was actually in base 13? Then:

	42(13) = 4×131 + 2×130 = 52 + 2 = 54 = 6×9
This is not a great secret because if you see the movie or television show, the opening credits show numbers in all sorts of bases, including 42(13).

If was just another one of Douglas Adams's little jokes.


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