-89.98% is the change from 639 to 64
Calculation steps:
[( 64 - 639 ) ÷ 639] x 100 = -89.98%
Formula
Percentage change = [(64 - 639) / 639] x 100
Subtract the new number by the original number
64 - 639 = -575
-575 ÷ 639 = -0.8998435054773083
-0.8998435054773083 x 100 = -89.98%