Question

what is the next series in 0.5,2.3,7.7,23.9, ?,218.3.

Answer 1

0.5
0.5 +1.8 = 2.3
2.3 + 1.8*3 = 7.7
7.7 + 1.8*3*3 = 23.9
23.9 + 1.8 *3*3*3 = 72.5
72.5 + 1.8 * 3^4 = 218.3