Inspired by an epiphany at age eleven:  the numbers and letters all came together one evening while I was doing my arithmatic homework.  Strangely enough, the next day was a Friday   AND  it was my teacher's birthday.  One girl's mother sent a large birthday sheet cake with fancy writing on it for she and her homeroom class to share.  I noticed there were no candles, but my friend Gene went further...too far.  "How come there aren't any candles on the cake Mrs. Richardson?  Were there too many? She looked quite taken back as I remember. A couple of the girls  'gasped', so to speak. One said, "Geeeene!"  Mrs. Richardson smiled and said, "Class...today I am 40 years old."  I was surprised, because she did not look that old to me.  She looked my mother's age, 32.  I gathered my nerve and said, "No, Mrs. Richardson; you're 39A!"  She asked for an explanation, which I eagerly gave. Just then, the Principal came in the room to offer his best wishes.  She said, "Mr. Reddington, today I am 39A!"  She explained my "system" to him and he was quite impressed. She was always especially nice to me after that.  And....one day a few weeks later, I overheard one teacher tell another that she was 39D.  I was proud.