Definition
Percent decrease
A decrease compared with the original value and written as a percent.
What it means
Find how much was lost, then compare that loss with the starting amount. A drop of 10 can be a small or large percent depending on what the value was at the start.
Remember it
Drop ÷ start × 100%.
Example
A price falls from $96 to $72. The decrease is $24, and 24 ÷ 96 = 0.25, so the price has a 25% decrease.
Watch for
Use percent decrease only when the new value is smaller than a positive original value. A zero original value cannot be used as the divisor.
Common mix-up
A decrease followed by the same percent increase usually does not return to the start because the second percent uses a different reference value.
Exact meaning
For a positive starting value and a smaller new value, percent decrease is (starting − new) ÷ starting × 100%. The starting amount supplies the denominator.