40 times 72 is 2880, but what is the answer if both 40 and 72 are negative numbers? Here we will determine if the answer to negative 40 times negative 72 is positive 2880 or negative 2880.
There are many different ways to explain and determine if the answer to negative 40 times negative 72 is -2880 or +2880 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 -2880 is the correct answer using basic algebra.
We will test if -2880 is correct by setting up the equation negative 40 times negative 72 equals negative 2880, and then simplifying the equation to see if it is true.
(-40) (-72) = (-2880)
Divide both sides of the equation by (-72) :
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| = |
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The numerator and denominator on the left side both have (-72) which even each other out and can be removed:
| (-40) = |
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The numerator and denominator on the right side both have a minus sign (-) which even each other out and can be removed:
| (-40) = |
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A numerator of 2880 and denominator of 72 on the right side is the same as 2880 divided by 72 which is 40. Now we end up with this untrue equation:
(-40) = (40)
-40 is NOT equal to 40, thus we have proven that negative 40 times negative 72 is not equal to -2880. The answer must therefore be 2880:
-40 x -72 = 2880
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 40 times negative 72 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 40 times negative 73?
Here is the next problem on our list that we have explained and calculated.
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