## arithmetic

Are you bored with 1 to 12? Then have a look at these mathematical clock faces!

Need to find the least common multiple or greatest common divisor of two numbers? A billiard table of the right proportions holds the answers!

There are some amazing patterns hiding within simple arithmetic.

How to write down unimaginably large numbers using just a few symbols.

Why do we add fractions the way we do? A very close look at addition reveals the answer — and it also works for negative numbers.

The Indian way of adding fractions makes things easier (with musical explanation).

How would you go about adding up all the integers from 1 to 100? Tap them into a calculator? Write a little computer code? Or look up the general formula for summing integers?

The number 1 can be written as a sum of unit fractions, that is fractions with 1 in the numerator. But how long can we make such a sum?