Really funny jokes-Numbers

The teacher asked little Andy if he knew his numbers yet. "Yes, teacher," he said, "my dad taught me."
"Good, Andy. Tell me what comes after two," the teacher said. "Three," replied Andy.
"Very good. What comes after five, Andy?" asked the teacher. "Six," answered Andy.
"Excellent. Your dad did a very good job. Now, what comes after ten?" the teacher asked.
"A jack!" replied Andy.