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

Asked by Aaron Moris

### Aaron Moris (view profile)

on 11 Apr 2011

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?

## Products

### Florin Neacsu (view profile)

Answer by Florin Neacsu

### 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

### Matt Fig (view profile)

Answer by Matt Fig

### Matt Fig (view profile)

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)

Answer by Paulo Silva

### Paulo Silva (view profile)

on 11 Apr 2011

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

### Doug Eastman (view profile)

Answer by Doug Eastman

### 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)

Answer by Matt Tearle

### 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.

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