-20.79% is the change from 813 to 644
Calculation steps:
[( 644 - 813 ) ÷ 813] x 100 = -20.79%
Formula
Percentage change = [(644 - 813) / 813] x 100
Subtract the new number by the original number
644 - 813 = -169
-169 ÷ 813 = -0.2078720787207872
-0.2078720787207872 x 100 = -20.79%