Question

Find the sum of first twelve multiples of 7.

Answer 1

546 is the sum of the first twelve of 7

Answer 2

First 12 multiples of  7 are= 7,14,21.......

a=7
d=7
n=12

s12= n/2{2a +(n-1)d}
s12= 12/2{2x7+(12-1)7}
    = 6(14+77)
   = 6(91)
   =546

The answer is 546.