Find the sum of the first 15 multiples of 8.

Given:

First 15 multiples of 8.

To do:

We have to find the sum of first 15 multiples of 8.

Solution:

First 15 multiples of 8 are:

$8, 16, 24,......, 104, 112, 120$

The above sequence is an A.P.

Here,

First term $a=8$, common difference $d =16-8=8$ and last term $l=120$

We know that,

Sum of first $n$ terms of an A.P. $=\frac{n}{2}(a+l)$

$=\frac{15}{2}( 8+120)$

$=\frac{15}{2}( 128)$

$=15\times64$

$=960$

Therefore, the sum of the first 15 multiples of 8 is 960.

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Updated on: 10-Oct-2022

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