Mathematics Problem of the Week

Spring 2004

POW 9

Digit Products

Let p(n) denote the product of the nonzero digits of n. For example, p(5) = 5, p(37) = 21, and p(604) = 24. Without resorting to a computer, evaluate:

p(1) + p(2) + p(3) + ... + p(999999).

Be sure to justify your answer.

Due Friday, April 2^nd , at Noon.

Solutions should be submitted to Dr. Maegan Bos' mailbox in the Math office or sent via e-mail to mbos@stlawu.edu.

Presentation counts! The prize-winning entry will be selected from all correct submissions, based on the clarity, creativity and elegance of the solution.

Look for the SLU POW on the Web at http://it.stlawu.edu/~math/activities/