40 times 4 is 160, but what is the answer if both 40 and 4 are negative numbers? Here we will determine if the answer to negative 40 times negative 4 is positive 160 or negative 160.
There are many different ways to explain and determine if the answer to negative 40 times negative 4 is -160 or +160 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 -160 is the correct answer using basic algebra.
We will test if -160 is correct by setting up the equation negative 40 times negative 4 equals negative 160, and then simplifying the equation to see if it is true.
(-40) (-4) = (-160)
Divide both sides of the equation by (-4) :
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| = |
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The numerator and denominator on the left side both have (-4) 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 160 and denominator of 4 on the right side is the same as 160 divided by 4 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 4 is not equal to -160. The answer must therefore be 160:
-40 x -4 = 160
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 40 times negative 4 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
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