What is negative 2 times negative 78? (-2 x -78)

What is negative 2 times negative 78?

2 times 78 is 156, but what is the answer if both 2 and 78 are negative numbers? Here we will determine if the answer to negative 2 times negative 78 is positive 156 or negative 156.

There are many different ways to explain and determine if the answer to negative 2 times negative 78 is -156 or +156 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 -156 is the correct answer using basic algebra.

We will test if -156 is correct by setting up the equation negative 2 times negative 78 equals negative 156, and then simplifying the equation to see if it is true.

(-2) (-78) = (-156)

Divide both sides of the equation by (-78) :

		(-2) (-78)
		(-78)

		(-156)
		(-78)

The numerator and denominator on the left side both have (-78) which even each other out and can be removed:

(-2) =

		(-156)
		(-78)

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

(-2) =

		(156)
		(78)

A numerator of 156 and denominator of 78 on the right side is the same as 156 divided by 78 which is 2. Now we end up with this untrue equation:

(-2) = (2)

-2 is NOT equal to 2, thus we have proven that negative 2 times negative 78 is not equal to -156. The answer must therefore be 156:

-2 x -78 = 156

The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 2 times negative 78 will always have a positive answer.

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