11 times 21 is 231, but what is the answer if both 11 and 21 are negative numbers? Here we will determine if the answer to negative 11 times negative 21 is positive 231 or negative 231.
There are many different ways to explain and determine if the answer to negative 11 times negative 21 is -231 or +231 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 -231 is the correct answer using basic algebra.
We will test if -231 is correct by setting up the equation negative 11 times negative 21 equals negative 231, and then simplifying the equation to see if it is true.
(-11) (-21) = (-231)
Divide both sides of the equation by (-21) :
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| = |
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The numerator and denominator on the left side both have (-21) which even each other out and can be removed:
| (-11) = |
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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:
| (-11) = |
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A numerator of 231 and denominator of 21 on the right side is the same as 231 divided by 21 which is 11. Now we end up with this untrue equation:
(-11) = (11)
-11 is NOT equal to 11, thus we have proven that negative 11 times negative 21 is not equal to -231. The answer must therefore be 231:
-11 x -21 = 231
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 11 times negative 21 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 11 times negative 22?
Here is the next problem on our list that we have explained and calculated.
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