3 Digits Plus 3 Digits

Date: 12/09/2001 at 14:41:51
From: Jake Cordell
Subject: Maths

Use the digits 1 to 9 only once in a sum that must be a three-digit 
number plus another three-digit number to equal another three-digit 
number. Each digit can only be used once, but all must be used.

Date: 12/09/2001 at 17:30:10
From: Doctor Sarah
Subject: Re: Maths

Hi Jake  - thanks for writing to Dr. Math.

The key here is that you will need a sum greater than 10 in the second 
row so as to be able to carry one to the first row when you add.

I'll give you one possibility for the second and third rows - see if 
you can come up with the first row:

   x    9    4

   x    8    2
   -----------
   x    7    6

Once you've found one solution, figure out how many ways you can 
switch the numbers to get another one.  (Hint: you can exchange 4 and 
2 and they will still add up to 6.)

Can you figure it out?

- Doctor Sarah, The Math Forum
  http://mathforum.org/dr.math/