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Write a program that calculates sum of the integers numbers

Asked by Aaron Moris on 11 Apr 2011
Latest activity Answered by caleb jemitola on 9 Oct 2017

What is the product if the question is write a program that calculates and prints the sum of the even integers from 2 to 30?

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6 Answers

Answer by Florin Neacsu on 11 Apr 2011

2+4+6+...+30=2(1+2+3+...+15)=2*(15*16)/2=15*16

So 2+4+...+n = floor(n/2)*(floor(n/2)+1).

Regards, Florin

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Answer by Loginatorist on 11 Apr 2011

The product would be the sum of the even integers from 2 to 30 ;-).

Seriously, what have you tried so far on this homework problem?

  2 Comments

You might need some bubble wrap for that.

I hate when it takes more time to understand what people want than to make their answer!

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Answer by Paulo Silva
on 11 Apr 2011

v=2:30;
sum(v(~mod(v,2)))  

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Hi Paulo, this works fine but what is operator ~ doing here? Its hard to understand what exactly is happening after ~. I am new to coding.

mod(v, 2) will be either 0 or 1. The tilde inverts that, so 0 becomes 1, and 1 becomes 0.

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Answer by Doug Eastman on 11 Apr 2011

or

sum(2:2:30)

  2 Comments

that's simple but if you change the start value from 2 to 1 you do the sum of odd numbers instead, also if the last value is 31 or some odd number the result won't be correct, unfortunately that's not very flexible code.

btw that does work and is a good answer for the question (only if the values don't change), +1 vote

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Answer by Matt Tearle
on 11 Apr 2011

disp(240)

Or, for pedants who claim that evaluation is not the same as calculation,

disp(239+1)

  1 Comment

This is definitely the most compact and efficient way to do this. +1.

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Answer by caleb jemitola on 9 Oct 2017

sum(2:2:30)

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