Wondering just how many sheep he currently has grazing in his field, the farmer asks his sheepdog to go out and count them.
The dog runs into the field, counts them, and then runs back to his master.
“So,” asks the farmer, “How many sheep are there?”
“40,” replies the dog.
“What? How can there be 40?!” exclaims the farmer. “I only bought 38!”
“I know,” says the dog. “But I rounded them up.”