What is negative 9 times negative 20? (-9 x -20)

What is negative 9 times negative 20?

9 times 20 is 180, but what is the answer if both 9 and 20 are negative numbers? Here we will determine if the answer to negative 9 times negative 20 is positive 180 or negative 180.

There are many different ways to explain and determine if the answer to negative 9 times negative 20 is -180 or +180 using mathematical terms such as additive inverse and mathematical laws like the Distribute Law.

We will take a different approach - process of elimination: We will simply test if -180 is the correct answer using basic algebra.

We will test if -180 is correct by setting up the equation negative 9 times negative 20 equals negative 180, and then simplifying the equation to see if it is true.

(-9) (-20) = (-180)

Divide both sides of the equation by (-20) :

		(-9) (-20)
		(-20)

		(-180)
		(-20)

The numerator and denominator on the left side both have (-20) which even each other out and can be removed:

(-9) =

		(-180)
		(-20)

The numerator and denominator on the right side both have a minus sign (-) which even each other out and can be removed:

(-9) =

		(180)
		(20)

A numerator of 180 and denominator of 20 on the right side is the same as 180 divided by 20 which is 9. Now we end up with this untrue equation:

(-9) = (9)

-9 is NOT equal to 9, thus we have proven that negative 9 times negative 20 is not equal to -180. The answer must therefore be 180:

-9 x -20 = 180

The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 9 times negative 20 will always have a positive answer.

Negative Times Negative Calculator
Here you can multiply another two negative numbers together.

What is negative 9 times negative 21?
Here is the next problem on our list that we have explained and calculated.