1 times 18 is 18, but what is the answer if both 1 and 18 are negative numbers? Here we will determine if the answer to negative 1 times negative 18 is positive 18 or negative 18.
There are many different ways to explain and determine if the answer to negative 1 times negative 18 is -18 or +18 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 -18 is the correct answer using basic algebra.
We will test if -18 is correct by setting up the equation negative 1 times negative 18 equals negative 18, and then simplifying the equation to see if it is true.
(-1) (-18) = (-18)
Divide both sides of the equation by (-18) :
|
| = |
|
The numerator and denominator on the left side both have (-18) which even each other out and can be removed:
| (-1) = |
|
The numerator and denominator on the right side both have a minus sign (-) which even each other out and can be removed:
| (-1) = |
|
A numerator of 18 and denominator of 18 on the right side is the same as 18 divided by 18 which is 1. Now we end up with this untrue equation:
(-1) = (1)
-1 is NOT equal to 1, thus we have proven that negative 1 times negative 18 is not equal to -18. The answer must therefore be 18:
-1 x -18 = 18
The above applies to all math problems where you multiply two negative numbers. Multiplying two negative numbers such as negative 1 times negative 18 will always have a positive answer.
Negative Times Negative Calculator
Here you can multiply another two negative numbers together.
What is negative 1 times negative 19?
Here is the next problem on our list that we have explained and calculated.
Copyright | Privacy Policy | Disclaimer | Contact