387.8% is the change from 82 to 400
Calculation steps:
[( 400 - 82 ) ÷ 82] x 100 = 387.8%
Formula
Percentage change = [(400 - 82) / 82] x 100
Subtract the new number by the original number
400 - 82 = 318
318 ÷ 82 = 3.8780487804878048
3.8780487804878048 x 100 = 387.8%