Question

Find the sum of the first 15 multiples of 8

Answer 1

First 20 multiples of 8
:8,16,24,32,40,48,56,64,72,80,88,86,104,112,120
Sum-960

Answer 2

just use the formula for finding the sum in AP.Just put the common difference as 8
                                  Sum=(N/2)(A+(M-1)d)
You will get the answer