I have a computer which will not used, however, it is about 4-5 years old already,
is it worth to use it to mine BTC?
If yes, how much will I expect to get in 1 month
is it worth to use it to mine BTC?
If yes, how much will I expect to get in 1 month
You will lose more power costs than you will earn something from it. There are special coins that are made for mining with a CPU though even then its not worth i.
I the case you now think about investing into hardware for mining bitcoins, please check before here: http://mining.thegenesisblock.com/
The biggest error most newbies do is not to realize that the profits are going down each month fast. So when you did not get your investment back in the first 2 or 3 months then you most probably will not make the investment back ever.
The same goes for cloud mining. Its simply way too hard.
I suggest stay out of it as long as you dont have some serious advantage, like power costs very low or so.