421.21% is the change from 66 to 344
Calculation steps:
[( 344 - 66 ) ÷ 66] x 100 = 421.21%
Formula
Percentage change = [(344 - 66) / 66] x 100
Subtract the new number by the original number
344 - 66 = 278
278 ÷ 66 = 4.212121212121212
4.212121212121212 x 100 = 421.21%