-19.49% is the change from 821 to 661
Calculation steps:
[( 661 - 821 ) ÷ 821] x 100 = -19.49%
Formula
Percentage change = [(661 - 821) / 821] x 100
Subtract the new number by the original number
661 - 821 = -160
-160 ÷ 821 = -0.19488428745432398
-0.19488428745432398 x 100 = -19.49%