99 times 91 is 9009, but what is the answer if both 99 and 91 are negative numbers? Here we will determine if the answer to negative 99 times negative 91 is positive 9009 or negative 9009.
There are many different ways to explain and determine if the answer to negative 99 times negative 91 is -9009 or +9009 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 -9009 is the correct answer using basic algebra.
We will test if -9009 is correct by setting up the equation negative 99 times negative 91 equals negative 9009, and then simplifying the equation to see if it is true.
(-99) (-91) = (-9009)
Divide both sides of the equation by (-91) :
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| = |
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The numerator and denominator on the left side both have (-91) which even each other out and can be removed:
| (-99) = |
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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:
| (-99) = |
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A numerator of 9009 and denominator of 91 on the right side is the same as 9009 divided by 91 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 91 is not equal to -9009. The answer must therefore be 9009:
-99 x -91 = 9009
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 99 times negative 91 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 99 times negative 92?
Here is the next problem on our list that we have explained and calculated.
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