72 times 30 is 2160, but what is the answer if both 72 and 30 are negative numbers? Here we will determine if the answer to negative 72 times negative 30 is positive 2160 or negative 2160.
There are many different ways to explain and determine if the answer to negative 72 times negative 30 is -2160 or +2160 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 -2160 is the correct answer using basic algebra.
We will test if -2160 is correct by setting up the equation negative 72 times negative 30 equals negative 2160, and then simplifying the equation to see if it is true.
(-72) (-30) = (-2160)
Divide both sides of the equation by (-30) :
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| = |
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The numerator and denominator on the left side both have (-30) which even each other out and can be removed:
| (-72) = |
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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:
| (-72) = |
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A numerator of 2160 and denominator of 30 on the right side is the same as 2160 divided by 30 which is 72. Now we end up with this untrue equation:
(-72) = (72)
-72 is NOT equal to 72, thus we have proven that negative 72 times negative 30 is not equal to -2160. The answer must therefore be 2160:
-72 x -30 = 2160
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 72 times negative 30 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 72 times negative 31?
Here is the next problem on our list that we have explained and calculated.
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