-21.63% is the change from 823 to 645
Calculation steps:
[( 645 - 823 ) ÷ 823] x 100 = -21.63%
Formula
Percentage change = [(645 - 823) / 823] x 100
Subtract the new number by the original number
645 - 823 = -178
-178 ÷ 823 = -0.21628189550425272
-0.21628189550425272 x 100 = -21.63%