-91.57% is the change from 830 to 70
Calculation steps:
[( 70 - 830 ) ÷ 830] x 100 = -91.57%
Formula
Percentage change = [(70 - 830) / 830] x 100
Subtract the new number by the original number
70 - 830 = -760
-760 ÷ 830 = -0.9156626506024096
-0.9156626506024096 x 100 = -91.57%