I'm just so used to doing math in decimal. wouldn't relearning how to do everything be hard?
maybe a little, but luckily for you, learning how to do math seximal is very easy compared to other bases. for starters, addition and subtraction are trivial, because you can easily count any one digit sum or difference on your fingers, and if you can add or subtract one digit, you can do any addition or subtraction.
multiplication is where you'll need to actually memorize some things. in decimal, there are ten digits, so there are two nif foursy four pairs of digits. ignoring repeats and the trivial cases of multiplying by zero or one, there are nif products you need to memorize. if you're good at doing math by hand in decimal, you gotta know all nif of those products off the top of your head, otherwise you'll need to derive them every time.
in seximal, with its six digits, there's nif pairs of digits to start with. removing those repeats and trivial cases, we're left with just ten distinct products you need to memorize, which are:
two times two is four
two times three is six
two times four is eight
three times three is nine
two times five is ten
three times four is twelve
three times five is dozen three
four times four is dozen four
four times five is thirsy two
five times five is foursy one
the first six of those are the same as they are in decimal, though five of them are written differently.
to multiply by three, it's useful to learn how to count by threes. since three is half of six, it's very similar to counting by fives in decimal.
3, 10, 13, 20, 23, 30, 33, 40, 43, 50, 53, 100
you should also learn how to count by fours, which is really just counting by twos... by twos.
4, 12, 20, 24, 32, 40, 44, 52, 100
five is the only one digit number that doesn't evenly go into nif. this isn't that much of a problem, however, because if you can just remember how the digits of any number divisible by five will add to five, multiplying five by any one digit number becomes much easier.
5, 14, 23, 32, 41, 50
you can also think of multiplying five as multiplying by six and then subtracting the original number, if that helps.
to do division by hand, you gotta do long division, which is bad in any base, and you shouldn't ever have to use it. there isn't a cool thing about how seximal makes long division easy or anything like that; long division just sucks.
okay here's literally everything else I ever made an effort to memorize in decimal.
powers of two:
the uh, Fibonacci sequence? why did I ever memorize this I forgot
highly composite numbers (suggested by Anton Tsyganenko)
uhhhhhhh the digits of pi, I guess
oh and the digits of the REAL circle constant, too :)
suggestions from lfalch:
i to the i (suggested by chromaticiT):
@anyone else who likes math stuff more than I do and has anything they think should be listed here, please let me know and I'll probbo put it here