-66.25% is the change from 640 to 216
Calculation steps:
[( 216 - 640 ) ÷ 640] x 100 = -66.25%
Formula
Percentage change = [(216 - 640) / 640] x 100
Subtract the new number by the original number
216 - 640 = -424
-424 ÷ 640 = -0.6625
-0.6625 x 100 = -66.25%