-23.54% is the change from 837 to 640
Calculation steps:
[( 640 - 837 ) ÷ 837] x 100 = -23.54%
Formula
Percentage change = [(640 - 837) / 837] x 100
Subtract the new number by the original number
640 - 837 = -197
-197 ÷ 837 = -0.23536439665471923
-0.23536439665471923 x 100 = -23.54%