-28.65% is the change from 897 to 640
Calculation steps:
[( 640 - 897 ) ÷ 897] x 100 = -28.65%
Formula
Percentage change = [(640 - 897) / 897] x 100
Subtract the new number by the original number
640 - 897 = -257
-257 ÷ 897 = -0.28651059085841696
-0.28651059085841696 x 100 = -28.65%