-21.89% is the change from 827 to 646
Calculation steps:
[( 646 - 827 ) ÷ 827] x 100 = -21.89%
Formula
Percentage change = [(646 - 827) / 827] x 100
Subtract the new number by the original number
646 - 827 = -181
-181 ÷ 827 = -0.218863361547763
-0.218863361547763 x 100 = -21.89%