-35.87% is the change from 998 to 640
Calculation steps:
[( 640 - 998 ) ÷ 998] x 100 = -35.87%
Formula
Percentage change = [(640 - 998) / 998] x 100
Subtract the new number by the original number
640 - 998 = -358
-358 ÷ 998 = -0.3587174348697395
-0.3587174348697395 x 100 = -35.87%