Triple summation?

Algebra Level 4

∑ i = 1 6 ∑ g = 1 i ∑ k = 1 g 1 = ? \large \displaystyle \sum_{i=1}^6 \sum_{g=1}^i \sum_{k=1}^g 1 =\, ?


The answer is 56.

Parth Lohomi by Parth Lohomi , 20, India

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3 solutions

Jaiveer Shekhawat
Nov 30, 2014

I haven't really laid my hands on multi-summation problems before and this was the first one, but I got the answer correct when I applied the below mentioned:

pp pp

16 Helpful 1 Interesting 1 Brilliant 0 Confused

Btw, you in which standard? @Parth Lohomi

Anuj Shikarkhane - 6 years, 6 months ago

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10th.........

Parth Lohomi - 6 years, 5 months ago
Finn Hulse
Sep 9, 2014

Pretty much, you can write it as 2 ( 6 ∗ 1 + 5 ∗ 2 + 4 ∗ 3 ) = 56 2(6*1+5*2+4*3)=\boxed{56} . :P

3 Helpful 0 Interesting 0 Brilliant 0 Confused
Ashwin K
Feb 12, 2016

Guys..this is a best example for nested FOR loop.

1 Helpful 0 Interesting 0 Brilliant 0 Confused

Python: 

sum(sum(sum(1 for k in range(1,g+1)) for g in range(1,i+1)) for i in range(1,7))

A Former Brilliant Member - 5 years, 2 months ago

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Yup u r r8

Sayandeep Ghosh - 5 years, 2 months ago

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