MATH PUZZLE: Can you replace...

It was many years ago since the embarrassing day when a young woman, with a baby in her arms, entered his butcher shop and confronted the butcher with the news that the baby was his and asked what was he going to do about it?

Finally he offered to provide her with free meat until the boy was 16. She agreed.

He had been counting the years off on his calender, and one day the teenager who had been collecting the meat each week, came into the shop and said, "I'll be 16 tomorrow."

"I know," said the butcher with a smile, "I've been counting too, tell your mother, when you take this parcel of meat home, that it is the last free meat she'll get, and watch the expression on her face."

When the boy arrived home he told his mother. The woman nodded and said, "Son, go back to the butcher and tell him I have also had free bread, free milk, and free groceries for the last 16 years and watch the expression on HIS face!"