Question

What is the next number of the series 1, 6, 26, 81? A.121 B.164 C.166 D.145

Answer 1

The rule goes as follows -
×5+1
×4+2
×3+3
×2+4

Therefore, 1×5+1 =6
6×4+2= 26
26×3+3= 81
81×2+4 = 166

Hope this helps :)