Which number should replace the question mark?

A young woman was preparing a ham dinner. After she cut off the end of the ham, she placed it in a pan for baking.

Her friend asked her,”Why did you cut off the end of the ham”?

And she replied ,”I really don’t know but my mother always did, so I thought you were supposed to.”

Later when talking to her mother she asked her why she cut off the end of the ham before baking it, and her mother replied, “I really don’t know, but that’s the way my mom always did it.”

A few weeks later while visiting her grandmother, the young woman asked, “Grandma, why is it that you cut off the end of a ham before you bake it?”

Her grandmother replied, “Well dear, otherwise it would never fit into my baking pan.”