Calculate total percent change from incremental changes

Question

Is there a formula to calculate a total percent change of a value from multiple changes?

Example:

Initial: 100
-10%: 90
+5%: 94.5
-20%: 75.6

So I am looking for some formulaic way of taking the initial value of 100 and the changes of -10%,+5%, and -20% and giving me 75.6.

Answer 1

Multiply all of the percent changes together as decimals i.e. 0.9*1.05*0.8 for your example and then multiply this number by the original value.