Last Night

I had consumed a small amount of calories all day so I had a 2 oz serving of whole wheat pasta with a half cup of canned spaghetti sauce. The pasta had 210 calories and the sauce 60 calories with one Tbl of parmesean (I don't know if I spelled it right) cheese that had 20 calories. That was a total of 290 calories. Then, my blood sugar went low in the night and instead of my usual high calorie nosh, I had a 100 calorie ice cream bar. This added up for a total of 1470. I aim for between 1330 and 1500 calories a day. How did I come up with this number? I read two different books and these are the numbers they gave me, so I shoot for between them.