-70.47% is the change from 640 to 189
Calculation steps:
[( 189 - 640 ) ÷ 640] x 100 = -70.47%
Formula
Percentage change = [(189 - 640) / 640] x 100
Subtract the new number by the original number
189 - 640 = -451
-451 ÷ 640 = -0.7046875
-0.7046875 x 100 = -70.47%