100.5% is the change from 398 to 798
Calculation steps:
[( 798 - 398 ) ÷ 398] x 100 = 100.5%
Formula
Percentage change = [(798 - 398) / 398] x 100
Subtract the new number by the original number
798 - 398 = 400
400 ÷ 398 = 1.0050251256281406
1.0050251256281406 x 100 = 100.5%