Code puzzle. please help solve it...

I recently came across this puzzle and am having great difficulty in solving it. If you work out the answer could you please email me on [email protected] or post here.here is the puzzle...

A code is given in two columns. The entry on the right for any row is the coded version for the entry on the left. Your task, should you accept it, is to determine the code entry for the fifth left entry.

Row Left Entry Coded Entry
1 623 674
2 284 518
3 1791 971
4 589 15
5 327 ???

thank you to all who try and help