-83.77% is the change from 610 to 99
Calculation steps:
[( 99 - 610 ) ÷ 610] x 100 = -83.77%
Formula
Percentage change = [(99 - 610) / 610] x 100
Subtract the new number by the original number
99 - 610 = -511
-511 ÷ 610 = -0.8377049180327869
-0.8377049180327869 x 100 = -83.77%