Hosted by The Math Forum

Problem of the Week 1025

Odd Couples

_____________________________________________
MacPoW Home ||  Forum PoWs ||  Teachers' Place ||  Student Center ||  Search MacPoW
_____________________________________________

Given any two digits, one can look at integers made up of those digits (using each at least once) and divisible by each of them. For example, if the digits are 2 and 4 then 24 is the smallest such number. If the digits are 2 and 5 then there is no such number, since it would have to be divisible by 10, and so have a 0. If the digits were 3 and 4, then the number is 3444.

For which pair of digits from 1,2,...,9 is this smallest number largest?

Source: Puzzles 101, by Nobuyuki Yoshigahara (AK Peters, Inc.), a collection of 101 delightful puzzles by a true master of the genre.

© Copyright 2005 Stan Wagon. Reproduced with permission.

[Privacy Policy] [Terms of Use]

_____________________________________
Home || The Math Library || Quick Reference || Search || Help 
_____________________________________

© 1994-2014 Drexel University. All rights reserved.
http://mathforum.org/
The Math Forum is a research and educational enterprise of the Drexel University School of Education.The Math Forum is a research and educational enterprise of the Drexel University School of Education.


8 February 2005