2 times 20 is 40, but what is the answer if both 2 and 20 are negative numbers? Here we will determine if the answer to negative 2 times negative 20 is positive 40 or negative 40.
There are many different ways to explain and determine if the answer to negative 2 times negative 20 is -40 or +40 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 -40 is the correct answer using basic algebra.
We will test if -40 is correct by setting up the equation negative 2 times negative 20 equals negative 40, and then simplifying the equation to see if it is true.
(-2) (-20) = (-40)
Divide both sides of the equation by (-20) :
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| = |
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The numerator and denominator on the left side both have (-20) which even each other out and can be removed:
| (-2) = |
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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:
| (-2) = |
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A numerator of 40 and denominator of 20 on the right side is the same as 40 divided by 20 which is 2. Now we end up with this untrue equation:
(-2) = (2)
-2 is NOT equal to 2, thus we have proven that negative 2 times negative 20 is not equal to -40. The answer must therefore be 40:
-2 x -20 = 40
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 2 times negative 20 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 2 times negative 21?
Here is the next problem on our list that we have explained and calculated.
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