Q. 154.8( 11 Votes )

Find the sum of the first 15 multiples of 8.

Answer :

First 15 multiples of 8 are 8, 16, 24, …, 120.

Sum of these numbers forms an arithmetic series 8 + 16 + 24 + … + 120.


Here, first term = a = 8


Common difference = d = 8


Sum of n terms of this arithmetic series is given by:


Sn = [2a + (n - 1)d]


Therefore sum of 15 terms of this arithmetic series is given by:


S15 = [2(8) + (15 - 1)(8)]


= (15/2) [16 + 112]


=(15/2) × 128


= 15 × 64


= 960


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Champ Quiz | Arithmetic Progression34 mins
Champ Quiz | Arithmetic Progression30 mins
Lets Check Your Knowledge in A.P.49 mins
Arithmetic progression: Previous Year NTSE Questions34 mins
Quiz on Arithmetic Progression Quiz32 mins
Arithmetic Progression Tricks and QUIZ37 mins
Quiz | Group of Questions on General Term of an A.P49 mins
Become a Master of A.P. in 45 Minutes!!47 mins
Get to Know About Geometric Progression41 mins
NCERT | Solving Questions on Introduction of A.P42 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses