-61.7% is the change from 671 to 257
Calculation steps:
[( 257 - 671 ) ÷ 671] x 100 = -61.7%
Formula
Percentage change = [(257 - 671) / 671] x 100
Subtract the new number by the original number
257 - 671 = -414
-414 ÷ 671 = -0.61698956780924
-0.61698956780924 x 100 = -61.7%