87 times 70 is 6090, but what is the answer if both 87 and 70 are negative numbers? Here we will determine if the answer to negative 87 times negative 70 is positive 6090 or negative 6090.
There are many different ways to explain and determine if the answer to negative 87 times negative 70 is -6090 or +6090 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 -6090 is the correct answer using basic algebra.
We will test if -6090 is correct by setting up the equation negative 87 times negative 70 equals negative 6090, and then simplifying the equation to see if it is true.
(-87) (-70) = (-6090)
Divide both sides of the equation by (-70) :
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| = |
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The numerator and denominator on the left side both have (-70) which even each other out and can be removed:
| (-87) = |
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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:
| (-87) = |
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A numerator of 6090 and denominator of 70 on the right side is the same as 6090 divided by 70 which is 87. Now we end up with this untrue equation:
(-87) = (87)
-87 is NOT equal to 87, thus we have proven that negative 87 times negative 70 is not equal to -6090. The answer must therefore be 6090:
-87 x -70 = 6090
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 87 times negative 70 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 87 times negative 71?
Here is the next problem on our list that we have explained and calculated.
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