-70.46% is the change from 870 to 257
Calculation steps:
[( 257 - 870 ) ÷ 870] x 100 = -70.46%
Formula
Percentage change = [(257 - 870) / 870] x 100
Subtract the new number by the original number
257 - 870 = -613
-613 ÷ 870 = -0.7045977011494253
-0.7045977011494253 x 100 = -70.46%