Find the sum of the first 15 multiples of 8.

Let to be a is first term and ‘d'” is common difference and l is last term of Given Arithmetic Sequence or Progression.

Arithmetic Sequence or Progression;- 8,16,24,32….

Here, First term= 8

Common Difference=8

Number of terms=15

We know that Formula of Summation of Arithmetic Sequence or Progression.

Sn=n/2(2a+(n-1)d)

S15=15/2(2×8+(15-1)8

=15/2(16+(14)8)

=15/2(16+112)

=15/2 x 128

=15 x 64

=960

The sum of the first 15 multiples of 8 is 960.