In addition and subtraction, if the plus sign is larger than the minus sign, then it's a plus. For example:

+10 minus -20 = -10

If the plus sign is smaller than the minus sign, the answer will be a minus.

For example:

-10 minus + 20 = -10

In multiplication, if you have 2 plus signs, the answer will be a plus sign. If you have 2 minus signs, the answer will be a plus sign then, too. But if you have a plus and a minus sign, then the answer will be a minus. For example:

+5 x + 2 = +10

-5 x - 2 = +10

-5 x +2 = -10

The person who invented the plus sign is the same as the minus

A plus times a plus is still a plus. Below is the way I remembered it:

If there is not a minus sign, it is plus (positive).

If there is 1 minus sign, it is minus (negative).

If there are 2 minus signs, it is plus (positive).

If you mean the ADDITIVE INVERSE, change the minus sign to a plus sign. (And if you see a plus sign, you change it to a minus sign.)

It indicates "plus or minus".