-90.21% is the change from 521 to 51
Calculation steps:
[( 51 - 521 ) ÷ 521] x 100 = -90.21%
Formula
Percentage change = [(51 - 521) / 521] x 100
Subtract the new number by the original number
51 - 521 = -470
-470 ÷ 521 = -0.9021113243761996
-0.9021113243761996 x 100 = -90.21%