-35.81% is the change from 997 to 640
Calculation steps:
[( 640 - 997 ) ÷ 997] x 100 = -35.81%
Formula
Percentage change = [(640 - 997) / 997] x 100
Subtract the new number by the original number
640 - 997 = -357
-357 ÷ 997 = -0.35807422266800404
-0.35807422266800404 x 100 = -35.81%