How do you count the calories in apples??

Please hear me out, this has been driving me crazy for months. On the back of a pack of apples it lists the nutrition info per 100g, but is that without the core and seeds?? Whenever I cut apples into slices, obviously removing those parts, I have no clue how to actually calculate the contents. Information online has been contradictory or just been about the whole apple weighted with the core. Help!