-74.38% is the change from 640 to 164
Calculation steps:
[( 164 - 640 ) ÷ 640] x 100 = -74.38%
Formula
Percentage change = [(164 - 640) / 640] x 100
Subtract the new number by the original number
164 - 640 = -476
-476 ÷ 640 = -0.74375
-0.74375 x 100 = -74.38%