## Write a program that calculates sum of the integers numbers

### Aaron Moris (view profile)

on 11 Apr 2011
Latest activity Answered by caleb jemitola

### caleb jemitola (view profile)

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?

### Florin Neacsu (view profile)

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

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?

Sean de Wolski

### Sean de Wolski (view profile)

on 11 Apr 2011

You might need some bubble wrap for that.

Paulo Silva

### Paulo Silva (view profile)

on 11 Apr 2011

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

### Paulo Silva (view profile)

on 11 Apr 2011

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

Brother_Devil

### Brother_Devil (view profile)

on 15 Aug 2017

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.

Image Analyst

### Image Analyst (view profile)

on 15 Aug 2017

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

### Doug Eastman (view profile)

on 11 Apr 2011

or

```sum(2:2:30)
```

Paulo Silva

### Paulo Silva (view profile)

on 11 Apr 2011

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.

Paulo Silva

### Paulo Silva (view profile)

on 11 Apr 2011

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

### Matt Tearle (view profile)

on 11 Apr 2011

```disp(240)
```

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

```disp(239+1)
```

Sean de Wolski

### Sean de Wolski (view profile)

on 11 Apr 2011

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

on 9 Oct 2017

sum(2:2:30)