9 times 19 is 171, but what is the answer if both 9 and 19 are negative numbers? Here we will determine if the answer to negative 9 times negative 19 is positive 171 or negative 171.
There are many different ways to explain and determine if the answer to negative 9 times negative 19 is -171 or +171 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 -171 is the correct answer using basic algebra.
We will test if -171 is correct by setting up the equation negative 9 times negative 19 equals negative 171, and then simplifying the equation to see if it is true.
(-9) (-19) = (-171)
Divide both sides of the equation by (-19) :
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| = |
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The numerator and denominator on the left side both have (-19) which even each other out and can be removed:
| (-9) = |
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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:
| (-9) = |
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A numerator of 171 and denominator of 19 on the right side is the same as 171 divided by 19 which is 9. Now we end up with this untrue equation:
(-9) = (9)
-9 is NOT equal to 9, thus we have proven that negative 9 times negative 19 is not equal to -171. The answer must therefore be 171:
-9 x -19 = 171
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 9 times negative 19 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 9 times negative 20?
Here is the next problem on our list that we have explained and calculated.
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