-87.75% is the change from 661 to 81
Calculation steps:
[( 81 - 661 ) ÷ 661] x 100 = -87.75%
Formula
Percentage change = [(81 - 661) / 661] x 100
Subtract the new number by the original number
81 - 661 = -580
-580 ÷ 661 = -0.8774583963691377
-0.8774583963691377 x 100 = -87.75%