13 times 39 is 507, but what is the answer if both 13 and 39 are negative numbers? Here we will determine if the answer to negative 13 times negative 39 is positive 507 or negative 507.
There are many different ways to explain and determine if the answer to negative 13 times negative 39 is -507 or +507 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 -507 is the correct answer using basic algebra.
We will test if -507 is correct by setting up the equation negative 13 times negative 39 equals negative 507, and then simplifying the equation to see if it is true.
(-13) (-39) = (-507)
Divide both sides of the equation by (-39) :
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| = |
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The numerator and denominator on the left side both have (-39) which even each other out and can be removed:
| (-13) = |
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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:
| (-13) = |
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A numerator of 507 and denominator of 39 on the right side is the same as 507 divided by 39 which is 13. Now we end up with this untrue equation:
(-13) = (13)
-13 is NOT equal to 13, thus we have proven that negative 13 times negative 39 is not equal to -507. The answer must therefore be 507:
-13 x -39 = 507
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 13 times negative 39 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 13 times negative 40?
Here is the next problem on our list that we have explained and calculated.
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