-85.85% is the change from 643 to 91
Calculation steps:
[( 91 - 643 ) ÷ 643] x 100 = -85.85%
Formula
Percentage change = [(91 - 643) / 643] x 100
Subtract the new number by the original number
91 - 643 = -552
-552 ÷ 643 = -0.8584758942457231
-0.8584758942457231 x 100 = -85.85%