39 times 4 is 156, but what is the answer if both 39 and 4 are negative numbers? Here we will determine if the answer to negative 39 times negative 4 is positive 156 or negative 156.
There are many different ways to explain and determine if the answer to negative 39 times negative 4 is -156 or +156 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 -156 is the correct answer using basic algebra.
We will test if -156 is correct by setting up the equation negative 39 times negative 4 equals negative 156, and then simplifying the equation to see if it is true.
(-39) (-4) = (-156)
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:
| (-39) = |
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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:
| (-39) = |
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A numerator of 156 and denominator of 4 on the right side is the same as 156 divided by 4 which is 39. Now we end up with this untrue equation:
(-39) = (39)
-39 is NOT equal to 39, thus we have proven that negative 39 times negative 4 is not equal to -156. The answer must therefore be 156:
-39 x -4 = 156
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 39 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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