Can I win some money mining bitcoin with an old computer I went to nicehash.com, a website that allows users to mine bitcoins.

I have my old computer on the side, it still work perfectly, but it's pretty slow. I could use it just for the fun of trying, if I win 50$/month I'm happy.

So I'm wondering, if I try to mine bitcoins, will I win a little money or will I lose some ??

I see 2 ways of actually losing money:

-if my computer is up all day, it will use electricity. If I never get paid, then I lose money in global.

-if my computer dies, I have to buy a new one.

So the two questions are: will I ever get paid, and how much ?

For the first question, I read somewhere that for each new transaction, several computers are ask to do so calculus, and the fastest computer often wins. The computer that wins get paid, the other are not. Is it exact ?

Thank you guys !
The short answer: No, you cannot. Sorry.

The longer answer can be found here: https://en.bitcoinwiki.org/wiki/Difficulty_in_Mining#How_soon_might_I_expect_to_generate_a_block.3F

Applying some common sense: If an old computer could mine for 50 USD / EUR / GBP per month, what do you think how many old computers would your neighbor have bought already and was running in his garage?

Bitcoin mining is only possible on specialized hardware these days. Your milage may vary on very, very recent high end GPUs, but this is far from an old unused PCs CPU power.