Project Euler Forum

In the problem it says the sum of the even valued terms that do not exceed 4million. But the answer is the first term over 4 million. This might need to be reworded.

Nathan

Why should the sum of the even valued fibonacci numbers less than 4 million not exceed 4 million?
The first fibonacci number that exceeds four million is 5702887. And that's not the correct answer.

So the individual terms to add must be less than 4 million, the sum does not need to be.

Hello
I'm french (nobody's perfect... ) and my english is bad ...
and I don't understand really
"Find the sum of all the even-valued terms in the sequence which do not exceed four million."
what is "even valued" ? why not only "all terms" ?
please can someone translate in french, or (better ?) give me the wanted sum for the first 10 terms for example ...
( 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 )
I can't solve this problem even if I've solve 20 others problems yet

thanks for help !

even numbers are numbers divisible by 2.
So you are asked to sum the Fibonacci numbers less than 4 million that are divisible by 2.

thank you very, very much !

(never I think this and automatic translate don't give this ...)

Sorry in advance for the long post ....
I completely understand the problem as it is stated. I wrote a quick brute force ruby program ... here it is ...

[snip]

I can't see what I'm doing wrong ... a nudge ... or a brick to the head ... in the right direction would be appreciated.

Thanks
Dave

I can verify that your answer is correct. Please edit your post to remove the answer and code to avoid spoiling it for anyone else.

I don't know why your answer wasn't accepted. Maybe a copy/paste brought in some extra characters. If the problem persists, maybe an admin can figure out what the problem is.

Whether it was a copy/paste slip or a server glitch, please try again and if that doesn't work, notify us.

Looks like it was a Copy/Paste glitch ... The one thing I didn't try was typing it in by hand. That's what I get for being lazy.
Sorry for the spoiler .... I'll remember that in the future ...

Thanks
Dave

Snipped out possible spoilers.
I don't think that makes for an efficient method: floats are slow compared to integers, moreover simple adding is much faster than multiplying or taking powers.
My prog based on the pdf runs in 0.003 milliseconds on a more than 4 years old computer using Delphi. (25 times as fast as yours)
Please do not post things like this again in the public part of this forum.

I'm having trouble with getting an answer for #2.
I have tried it for smaller numbers (limit 55) and I get 44 (34 + 8 + 2) for the answer. When I enter 4000000 as my limit, I get the wrong answer. Is there something I am missing about this problem?

Probably. Keep plugging away at it; you'll get there in the end. Good luck
_{(please note: this is not a hints forum!)}

But if it works for a smaller number, it should work for a larger number as well.
I think the problem is my answers are coming out to be in the format X.XXXe+00X, because I tried problem 6 and it also said it was wrong.

So if my answer is 1.111e+003, the correct answer should be 1111 right?
(^ not an answer I got for either problem, just the same format).

try using integers instead of floats/doubles.

what programming language do you use?

stijn263 wrote:try using integers instead of floats/doubles.

what programming language do you use?

C++

chinesefishmarket wrote:

stijn263 wrote:try using integers instead of floats/doubles.

what programming language do you use?

C++

OK. Forcing everything to be int works out great.
Thank you.

Yup, you should avoid using doubles unless you have a good reason for using them. All projecteuler problems have answers smaller than 2⁶³, so using long long int will be sufficient.

If you're using cout to output your numbers, you can change the precision of the double output by setting: cout.precision(15);

Ints will always be fully shown.

Hi, I looked over a previous post on #2 but I'm still confused. In my understanding, am I to find:

[1] the sum of all the even numbers and the sum should be less than or equal to 4 million?

[2] the sum of the even numbers under each of which is less than or equal to 4 million? In this case, the answer can be greater than 4 million.

Which way am I supposed to solve it?

Thank you

It is case [2]. Each of the numbers must be smaller or equal 4 million.

I give up...for today. I thought I got the numbers but I keep getting it wrong. My code must be bad. I'm using matlab.