80% is the change from 555 to 999
Calculation steps:
[( 999 - 555 ) ÷ 555] x 100 = 80%
Formula
Percentage change = [(999 - 555) / 555] x 100
Subtract the new number by the original number
999 - 555 = 444
444 ÷ 555 = 0.8
0.8 x 100 = 80%
Example