19 times 18 is 342, but what is the answer if both 19 and 18 are negative numbers? Here we will determine if the answer to negative 19 times negative 18 is positive 342 or negative 342.
There are many different ways to explain and determine if the answer to negative 19 times negative 18 is -342 or +342 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 -342 is the correct answer using basic algebra.
We will test if -342 is correct by setting up the equation negative 19 times negative 18 equals negative 342, and then simplifying the equation to see if it is true.
(-19) (-18) = (-342)
Divide both sides of the equation by (-18) :
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| = |
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The numerator and denominator on the left side both have (-18) which even each other out and can be removed:
| (-19) = |
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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:
| (-19) = |
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A numerator of 342 and denominator of 18 on the right side is the same as 342 divided by 18 which is 19. Now we end up with this untrue equation:
(-19) = (19)
-19 is NOT equal to 19, thus we have proven that negative 19 times negative 18 is not equal to -342. The answer must therefore be 342:
-19 x -18 = 342
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 19 times negative 18 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
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