Can you replace the question mark with a number?

A woman walked up to a little old man rocking in a chair on his porch.
"I couldn't help noticing how happy you look," she said. "What's your secret for a long happy life?"
"I smoke three packs of cigarettes a day," he said. "I also drink a case of whiskey a week, eat fatty foods, and never exercise."
"That's amazing," the woman said. "How old are you?'
"Twenty-six," he said.