Binary Arithmetic is like regular arithmetic, but using binary rather than decimal numbers. In most computers, it is done with a fixed word size, with an extra bit to handle carry-over for exceeding it. See also BooleanLogic.
BinaryArithmetic is an example where simplification makes something very easy: Multiplication in decimal requires memorizing the times table, but in binary it is basically a copy. Example:
100101 * 101001 = 37 * 41 --------------- ------- 100101 148 (37*4=120+28) 000000 37 (37*1) 100101 ---- 000000 1 <- carry 000000 1517 100101 --------------- 1 <- carry 10111101101 = 1517