66.22% is the change from 521 to 866
Calculation steps:
[( 866 - 521 ) ÷ 521] x 100 = 66.22%
Formula
Percentage change = [(866 - 521) / 521] x 100
Subtract the new number by the original number
866 - 521 = 345
345 ÷ 521 = 0.6621880998080614
0.6621880998080614 x 100 = 66.22%