Fun with numbers

The publisher of our local paper entertained us with some numerology in his most recent column ("Unfollow this link shortener", Feedback section).

Among the baubles are this one: “Take the last two numbers of the year of your birth, add what your age is this year, and you’ll get 111.” Except when you don’t.

No magic here, after all, because we are only saying that the year of your birth plus your age should equal the current year.

But to get 111 in particular, another condition must hold – that “you” must have been born in the last century. My nephew, for instance, born in 2001, calculates out to 11, not 111. And Abe Lincoln, born in 1809 and 202 years old, yields 211.

The leftmost digit (hundreds position) does carry some information, however. In the case of Abe Lincoln, 2 indicates how many centuries his birth is removed from the current one. And in my nephew's case, zero hundreds likewise indicates that he was born in this century.

Number puzzles can be fun. For me, the most fun comes from decomposing them and poking around the edges. Not mind-bending stuff, but pleasant over a cup of coffee on a rainy Sunday morning.