-2.27% is the change from 661 to 646
Calculation steps:
[( 646 - 661 ) ÷ 661] x 100 = -2.27%
Formula
Percentage change = [(646 - 661) / 661] x 100
Subtract the new number by the original number
646 - 661 = -15
-15 ÷ 661 = -0.0226928895612708
-0.0226928895612708 x 100 = -2.27%