"Yes," he said. "I do. My father taught me."

"Good. What comes after three?"

"Four," answers little Johnny.

"What comes after six?"

"Seven."

"Very good," says the teacher. "Your dad did a good job. What comes after ten?"

Little Johnny smiles and says, "A Jack."

The Answer to Yesterday's Useless Riddle:
There is a town in California where 10% of all the people living there have unlisted phone numbers. If you selected 100 names at random from the town's phone directory, on average, how many of these people would have unlisted phone numbers?
Answer:   Zero. Unlisted phone numbers are NOT in the phone directory.