Arithmetic Course/Number Operation/Multiplication

Multiplication
Addition is the operation of adding (combining) two quantities which can be represented by
 * A x B

Operation

 * a x b = b x a
 * a x b x c = a x (b x c) = (a x b) x c

Rules
Any number multiply by zero is equal to zero
 * a + 0 = a

Any number multiply to itself is
 * a x a = a2

Any negative number multiply by itself is
 * (-a) x (-a) = a2

Any number multiply to its negative is
 * a x (-a) = -a2