686.9% is the change from 84 to 661
Calculation steps:
[( 661 - 84 ) ÷ 84] x 100 = 686.9%
Formula
Percentage change = [(661 - 84) / 84] x 100
Subtract the new number by the original number
661 - 84 = 577
577 ÷ 84 = 6.869047619047619
6.869047619047619 x 100 = 686.9%