What is negative 99 times negative 72? (-99 x -72)

What is negative 99 times negative 72?

99 times 72 is 7128, but what is the answer if both 99 and 72 are negative numbers? Here we will determine if the answer to negative 99 times negative 72 is positive 7128 or negative 7128.

There are many different ways to explain and determine if the answer to negative 99 times negative 72 is -7128 or +7128 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 -7128 is the correct answer using basic algebra.

We will test if -7128 is correct by setting up the equation negative 99 times negative 72 equals negative 7128, and then simplifying the equation to see if it is true.

(-99) (-72) = (-7128)

Divide both sides of the equation by (-72) :

		(-99) (-72)
		(-72)

		(-7128)
		(-72)

The numerator and denominator on the left side both have (-72) which even each other out and can be removed:

(-99) =

		(-7128)
		(-72)

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

(-99) =

		(7128)
		(72)

A numerator of 7128 and denominator of 72 on the right side is the same as 7128 divided by 72 which is 99. Now we end up with this untrue equation:

(-99) = (99)

-99 is NOT equal to 99, thus we have proven that negative 99 times negative 72 is not equal to -7128. The answer must therefore be 7128:

-99 x -72 = 7128

The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 99 times negative 72 will always have a positive answer.

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