The *n*-th birthday of a very famous mathematician coincides with a year that corresponds to the (*n*+1)st prime number. Who is this mathematician?

**Answer:** Leonhard Euler (15 April 1707-18 September 1783). His 304th birthday coincides with this year 2011, which happens to be the 305th prime number.

*This puzzle was contributed by Aziz Inan, Professor of Electrical Engineering at the University of Portland. His own name, when written in capital letters, is a geometric word puzzle. Swap the vowels and turn the consonants 90 degrees and the words have switched places. "My parents didn't plan this," he says. "It's just fun."*

## Comments

## Prime birthday

Is this correct?

Hypatia (370-415)

Hypatias 87th birthday coincides with the year 457.

88th prime is 457.

yours Reino Anttila