Well, I guess he did. I never heard of it.
OK, quick: Who's U.S. Grant minus John Quincy Adams? My six-year-old can tell you. We were somewhat flummoxed the first time he asked us. He waited, patiently, and finally offered: That's hard, it's OK, I'll tell you.
BTW, it's Zachary Taylor. I had to look it up.
(Update: Oh dear savior. For a lark, I just asked him who James Madison times James Madison is. He didn't even hesitate or stop playing X-Box: Abe Lincoln. He rattled off a half dozen more answers multiplying one President by another to yield a third. I'm going back to the hospital right now to demand they give me the correct baby)