Lou Zerr is trying to pick up a woman at a bar. The woman, Denise, is reluctant to give out her number, but she gives Lou a clue.

"My sister, Elise and I have the same digits in our phone numbers, just in reverse order. Elise's number is also evenly divisible by mine."

What is Denise's phone number?

(Note: this IS NOT a real exchange, as far as I know. Assume the phone number has 10 digits: 7 digit number + 3 digit area code.)

(In reply to re: Another non-trivial solution by Penny)

Penny: I don't think either of your answers are valid. The question states that "Elise's number is... evenly divisible by [Denise's]" whereas both of your solutions have division by 9. Maybe it's another interpretation thing (cf the and/or discussion), but I took 'evenly divisible' to mean 'divides with an even answer' (ie 0,2,4,6,8).

This should cut down your search as it means that Elise's number must end in an even number (ergo Denise's must start with an even number).

Posted by fwaff on 2004-04-19 10:27:12