which is the real tonnage - capacity of the ipad mini retina 64gb?

i bought the ipad mini rhetina 64gb and when i opened it i saw that the tonnage - capacity is 56,60GB

why?

by the way i bought it totaly closed with gelatin and packed with all apple details from apple store. but i discover when i opened it that the battery was charged 85% and the itunes was already inside the ipad without me have downloaded it before.

pls inform if i have bought brand new ipad mini retina or it is second hand??