I just have to point out that the comma thing varies between English speaking countries and some other countries.
All of continental Europe uses comma instead of full stop, for numbers.
I don't know about Russia.

So 4,5 years is how most Europeans write 4.5 years.
And a price is written 9,90 € rather than £9.90

It occassionally causes some confusion as people forget this, or don't know about it, and occassionally IT problems too.