Why does a negative time a negative equal a positive?

Solution:

We know that negative times anything means that it will change the sign. 

Now, let's have a negative number. We multiply it with another negative number. For example, -3 × - 9 = 27

Ideally, the second negative should change the sign of our original number (which is also negative). 

So, our original negative sign is changed into a positive sign when a negative is multiplied to it. 

Thus, As multiplying with negative will change the sign, a negative times a negative equal a positive. 

Why does a negative time a negative equal a positive?

Summary:

As multiplying with negative will change the sign, a negative times a negative equal a positive