Odds the board pairs?

[other1]

What are the odds of the board pairing? Any two cards at any point.. I calculated it as 25% but that feels wrong to me..

I'm basically figuring..

First card, 0/52
Second card, 3/51 (3 chances to pair previous)
Third card, 6/50 (3 chances to pair either previous)
Turn, 9/49 (etc..)
River, 12/48

Am I retarded? [img]/images/graemlins/blush.gif[/img]