80 times 1 is 80, but what is the answer if both 80 and 1 are negative numbers? Here we will determine if the answer to negative 80 times negative 1 is positive 80 or negative 80.
There are many different ways to explain and determine if the answer to negative 80 times negative 1 is -80 or +80 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 -80 is the correct answer using basic algebra.
We will test if -80 is correct by setting up the equation negative 80 times negative 1 equals negative 80, and then simplifying the equation to see if it is true.
(-80) (-1) = (-80)
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:
| (-80) = |
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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:
| (-80) = |
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A numerator of 80 and denominator of 1 on the right side is the same as 80 divided by 1 which is 80. Now we end up with this untrue equation:
(-80) = (80)
-80 is NOT equal to 80, thus we have proven that negative 80 times negative 1 is not equal to -80. The answer must therefore be 80:
-80 x -1 = 80
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 80 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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