-15.97% is the change from 620 to 521
Calculation steps:
[( 521 - 620 ) ÷ 620] x 100 = -15.97%
Formula
Percentage change = [(521 - 620) / 620] x 100
Subtract the new number by the original number
521 - 620 = -99
-99 ÷ 620 = -0.1596774193548387
-0.1596774193548387 x 100 = -15.97%