Question

In the series of number 6 , 12 , 24 , ... what is sum of the first 6 numbers

Answer 1

sum of no. = n/2(2a+(n-1)d)

a=6, d=12-6=6

n=6

put these values in the formula

6/2(2*6+(6-1)6)

3(12+5*6)

3(12+30)

3*42

126

hopefully you will get it