The rule i learned is:

For multiplication or division two likes give a positive answer, two unlikes give a negative answer.

E.g.

-2 * -2 = 4

-2 * 2 = -4

BUT look at this...

2 * 2 = 4 is the same as saying 2 + 2 = 4. Right?So....

-2 * -2 = 4 should be the same as saying -2 + -2 = x

But... -2 + -2 = -2 - 2 = -4 ..... so it isn't the same pattern as above.

Can anyone shed some light?