-21.75% is the change from 823 to 644
Calculation steps:
[( 644 - 823 ) ÷ 823] x 100 = -21.75%
Formula
Percentage change = [(644 - 823) / 823] x 100
Subtract the new number by the original number
644 - 823 = -179
-179 ÷ 823 = -0.2174969623329283
-0.2174969623329283 x 100 = -21.75%