-3.03% is the change from 661 to 641
Calculation steps:
[( 641 - 661 ) ÷ 661] x 100 = -3.03%
Formula
Percentage change = [(641 - 661) / 661] x 100
Subtract the new number by the original number
641 - 661 = -20
-20 ÷ 661 = -0.030257186081694403
-0.030257186081694403 x 100 = -3.03%