72 times 17 is 1224, but what is the answer if both 72 and 17 are negative numbers? Here we will determine if the answer to negative 72 times negative 17 is positive 1224 or negative 1224.
There are many different ways to explain and determine if the answer to negative 72 times negative 17 is -1224 or +1224 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 -1224 is the correct answer using basic algebra.
We will test if -1224 is correct by setting up the equation negative 72 times negative 17 equals negative 1224, and then simplifying the equation to see if it is true.
(-72) (-17) = (-1224)
Divide both sides of the equation by (-17) :
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| = |
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The numerator and denominator on the left side both have (-17) which even each other out and can be removed:
| (-72) = |
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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:
| (-72) = |
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A numerator of 1224 and denominator of 17 on the right side is the same as 1224 divided by 17 which is 72. Now we end up with this untrue equation:
(-72) = (72)
-72 is NOT equal to 72, thus we have proven that negative 72 times negative 17 is not equal to -1224. The answer must therefore be 1224:
-72 x -17 = 1224
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 72 times negative 17 will always have a positive answer.
Negative Times Negative Calculator
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