One cup of kidney beans contains 15 g of protein, 1 g of fat, and 42 g of carbohydrate. how many kilocalories, to two significant figures, does this sample contain? (the caloric values are: 4 kcal/g for carbohydrate, 9 kcal/g for fat, and 4 kcal/g for protein.)

 we need to get the total calories, we can get it by getting the average of calories of the protein, fat, and carbohydrates:
calories of protein = 15g x 4 KCal/g
                               = 60 KCal
calories of fat = 1 g x 9 KCal/g
                        = 9 kCal
calories of carbohydrates = 42 g x 4 KCal/g 
                                            = 168 Kcal
∴ the total calories = 60 + 9 + 168 = 237Kcal = 0.237 Cal
to get the resualt to two significant figures 
∴ the resault is = 0.24 Cal = 240 KCal

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.

Ido not understand.