Easy Logic Puzzle

Originally posted by wolfgang59
That was trhe answer I was after but my initial problem did lead to multiple answers. I should have phrased it thus;

1st guy: "I dont know your number"
2nd guy: "I dont know your number"
1st guy: "I dont know your number"
[b]3rd guy to 1st guy: "I know your number"

What was N?[/b]