That would never work. You'd find some garbage in the output, or even worse, get a core dump due to n being undefined. I think you mean 2x * 1000. .... or I've been refactoring my code for too long.

But yes, this is generally the rule I use as well, take the hourly rate and double it and add a K (eg $30/hr = $60K)

Doesn't include holidays, sick leave or efficiency trade-offs (billable time vs maintenance, research). Personally I use an estimate of about 75% efficiency to get a realistic answer, so then your formula becomes 3/4 * x * 1000

So at $175/hr I'd expect something like 130,000 annually. Given that its said he's quite frugal and doesn't mind hard work, it could well end up being around the 250-300K, but I'd expect he'd end up burning out after a year or 3.