Nursing Home Math Logic

A doctor at a nursing home is checking the mental state of three patients.

He asks the first patient, "What is three times three?" The patient answers, "810,958." He asks the second patient, "What is three times three?" The patient replies, "Tuesday." He asks the third patient, "What is three times three?" The patient says, "Nine." Impressed, the doctor asks, "How did you figure that out?" "It was simple," the man replies. "I divided 810,958 by Tuesday."