400% is the change from 64 to 320
Calculation steps:
[( 320 - 64 ) ÷ 64] x 100 = 400%
Formula
Percentage change = [(320 - 64) / 64] x 100
Subtract the new number by the original number
320 - 64 = 256
256 ÷ 64 = 4
4 x 100 = 400%
Example