290.8% is the change from 87 to 340
Calculation steps:
[( 340 - 87 ) ÷ 87] x 100 = 290.8%
Formula
Percentage change = [(340 - 87) / 87] x 100
Subtract the new number by the original number
340 - 87 = 253
253 ÷ 87 = 2.9080459770114944
2.9080459770114944 x 100 = 290.8%