31 times 28 is 868, but what is the answer if both 31 and 28 are negative numbers? Here we will determine if the answer to negative 31 times negative 28 is positive 868 or negative 868.
There are many different ways to explain and determine if the answer to negative 31 times negative 28 is -868 or +868 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 -868 is the correct answer using basic algebra.
We will test if -868 is correct by setting up the equation negative 31 times negative 28 equals negative 868, and then simplifying the equation to see if it is true.
(-31) (-28) = (-868)
Divide both sides of the equation by (-28) :
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| = |
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The numerator and denominator on the left side both have (-28) which even each other out and can be removed:
| (-31) = |
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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:
| (-31) = |
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A numerator of 868 and denominator of 28 on the right side is the same as 868 divided by 28 which is 31. Now we end up with this untrue equation:
(-31) = (31)
-31 is NOT equal to 31, thus we have proven that negative 31 times negative 28 is not equal to -868. The answer must therefore be 868:
-31 x -28 = 868
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 31 times negative 28 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 31 times negative 29?
Here is the next problem on our list that we have explained and calculated.
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