309.8% is the change from 51 to 209
Calculation steps:
[( 209 - 51 ) ÷ 51] x 100 = 309.8%
Formula
Percentage change = [(209 - 51) / 51] x 100
Subtract the new number by the original number
209 - 51 = 158
158 ÷ 51 = 3.0980392156862746
3.0980392156862746 x 100 = 309.8%