If subtraction is taking an amount away from another amount, what does it mean to take an amount away from a negative amount?
Remember that subtraction is the same as addition, but in the opposite direction. On the number line, subtraction is shown by moving to the left. If our starting number is already negative, then moving to the left makes our solution a larger negative number.
This concept is most familiar when it comes to temperature. If it is -5 degrees and the temperature gets 10 degrees colder, the temperature can be calculated as the following:
\(-5 - 10 = -5 + (-10) = -15\)
Another example is debt. If I am $1000 in debt and I spend another $500, I subtract 500 from -1000. This is shown as the following:
\(-1000 - 500 = -1000 + (-500) = -1500\)
If the starting number is negative and we subtract a number from it, we add the numbers together, but the answer is a larger negative number.
Practice ProblemsEvaluate the following expression:
- \(-2 - 3 = ?\) (Solution
- \(-4 - 4 = ?\) (Solution
- \(-5 - 2 = ?\) (Solution
- \(-17 - 2 = ?\) (Video Solution
- \(-10 - 15 = ?\) (Solution
- \(-46 - 15 = ?\) (Video Solution
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