Primecoins are not easy to mine. I had 280 cpu cores pointed at it and was only able to get about 20 per day. That was back in November. I'm sure it still around there. So with a single cpu, well you ain't gettin' much... You would be better off mining a coin like Frozen.
This calculator must be jacked up :
http://anty.info/primecoin-calculator/How many chains per day did you get back then?
Not 100% sure. I was mining on ypool so we were finding most blocks. The problem is there were 60,000 workers on that pool mining. My take from each block was .01 to .05 depending on the time of day. Back in September I was getting about .10 to .30 per block. Much better back then, I should have bought more VPS accounts then. Oh well..