-79.69% is the change from 64 to 13
Calculation steps:
[( 13 - 64 ) ÷ 64] x 100 = -79.69%
Formula
Percentage change = [(13 - 64) / 64] x 100
Subtract the new number by the original number
13 - 64 = -51
-51 ÷ 64 = -0.796875
-0.796875 x 100 = -79.69%
Example