You make a arithmetic problem out of letters which have associated number values, and make a cool phrase like this. You can try to decipher this one:
SEND+MORE=MONEY
or put this way
SEND
+MORE
-----
MONEY
so, since the letters are all digits from 0-9, and we know that S + M creates a carry, that carry (M) must be 1. You can use logic and modular arithmetic to derive the values for the remainder of the letters. Cool...
