-61.72% is the change from 640 to 245
Calculation steps:
[( 245 - 640 ) ÷ 640] x 100 = -61.72%
Formula
Percentage change = [(245 - 640) / 640] x 100
Subtract the new number by the original number
245 - 640 = -395
-395 ÷ 640 = -0.6171875
-0.6171875 x 100 = -61.72%