-83.59% is the change from 640 to 105
Calculation steps:
[( 105 - 640 ) ÷ 640] x 100 = -83.59%
Formula
Percentage change = [(105 - 640) / 640] x 100
Subtract the new number by the original number
105 - 640 = -535
-535 ÷ 640 = -0.8359375
-0.8359375 x 100 = -83.59%