How many calories do I need to consume a day to gain 12-15 pounds in 9 weeks (10 Points BA)?

All this math crap is confusing me -__-. I know my BMR is 1673.1 So how much/how many calories would I have to eat a day to gain 12-15 pounds in 9 weeks? I plan on eating healthy foods such as nuts, fruit, pasta, etc.