[david hutchinson]

david hutchinson asked the Naked Scientists:
   
how many permutations are there in a sudoko grid?

What do you think?

[imatfaal]

There are 5,472,730,538 unique sudoko arrangements.  Each of these can be made into a thousand or so more by row changes, column changes and rotations (ie you can always swap row 1 and row 3 and have a valid solution).

It is currently thought you need at least 17 numbers to uniquely specify the grid

The Number Mysteries - Marcus Du Sautoy page 163