91 times 1 is 91, but what is the answer if both 91 and 1 are negative numbers? Here we will determine if the answer to negative 91 times negative 1 is positive 91 or negative 91.
There are many different ways to explain and determine if the answer to negative 91 times negative 1 is -91 or +91 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 -91 is the correct answer using basic algebra.
We will test if -91 is correct by setting up the equation negative 91 times negative 1 equals negative 91, and then simplifying the equation to see if it is true.
(-91) (-1) = (-91)
Divide both sides of the equation by (-1) :
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| = |
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The numerator and denominator on the left side both have (-1) which even each other out and can be removed:
| (-91) = |
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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:
| (-91) = |
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A numerator of 91 and denominator of 1 on the right side is the same as 91 divided by 1 which is 91. Now we end up with this untrue equation:
(-91) = (91)
-91 is NOT equal to 91, thus we have proven that negative 91 times negative 1 is not equal to -91. The answer must therefore be 91:
-91 x -1 = 91
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 91 times negative 1 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
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