830.95% is the change from 42 to 391
Calculation steps:
[( 391 - 42 ) ÷ 42] x 100 = 830.95%
Formula
Percentage change = [(391 - 42) / 42] x 100
Subtract the new number by the original number
391 - 42 = 349
349 ÷ 42 = 8.30952380952381
8.30952380952381 x 100 = 830.95%