-87.07% is the change from 642 to 83
Calculation steps:
[( 83 - 642 ) ÷ 642] x 100 = -87.07%
Formula
Percentage change = [(83 - 642) / 642] x 100
Subtract the new number by the original number
83 - 642 = -559
-559 ÷ 642 = -0.8707165109034268
-0.8707165109034268 x 100 = -87.07%