List sorting

List sorting

Hi,

I have attached a reference image. The last column is of Floor No. As you can see the sorting of floor is not coming out correct. We tried adding '0' in the front of every single number (1 to 01, 2 to 02 and so on) so that it is displayed on the top but somehow it is resetting every time. But in the 2nd last column(Apartment No.) it is not resetting.
Now how we need list to display is - 1st sort by Floor No. and then Apartment no. How can we 
achieve this.