Why multiply a negative number in a negative number that gives a positive number ?!

Let's try math (-2 * -3)

   -2 * -3 = (-1) (2) (- 1) (3)

             = (-1) (- 1) (2) (3)

             = (-1) (- 1) * 6

The question here, what is the value of -1 * -1? Either it is -1 or +1, and if we say it is + 1, the correct answer will be output 6.

But what if we assumed that (-1 * -1) = -1, what would happen?

Calculate this process (-1) (1 + -1) assuming that multiplying two negative numbers gives a negative number.

(-1) (-1 + -1) = (-1) (1) + (-1) (- 1)

         (-1) (0) = -1 + -1

               0 = -2

Of course, this is wrong at all. Zero is not negative. If you calculate that a negative number multiplied by a negative number gives a positive number, then the result

(-1) (-1 + -1) = (-1) (1) + (-1) (- 1)

         (-1) (0) = -1 + 1

               0 = 0