[Guest]

Ok, what is the least amount of numbers you can fill into

that will yield only one result

Just follow standard Sudoku rules when filling it out which are as follows:

1. Each row must contain exactly 1 of each number 1 through 9

2. Each column must contain exactly 1 of each number 1 through 9

3. Each 3x3 box that I have thickened the border around must contain exactly one of each number 1 through 9

If that's not clear enough for you just Google Sudoku and i'm sure there are plenty of sites that explain the rules better than that

Challenge: Try a 16x16 grid and find the least amount of spaces that must be filled in (note that the numbers will range from 1 to 16 instead of 1 to 9, and instead of having 3x3 boxes as in Rule #3 they will be 4x4 boxes)

Please don't just give me a number, show your logic/math behind your answer.

And for clarification, when solving it it is allowed for you to have no way of knowing exactly what a certain square must be without guessing/checking each number, just make sure there is only 1 number that will eventually work out into that spot

[andromeda]

Hm...

I think I read it somewhere and I know the number (that I won't post) because I don't know the explanation...

[Guest]

Yes please don't post without an explanation =)

Try this with a 4x4 grid using 4 sets of 2x2 boxes with numbers 1-4, might help some of you or at least give you ideas

[Guest]

Yes please don't post without an explanation =)

Try this with a 4x4 grid using 4 sets of 2x2 boxes with numbers 1-4, might help some of you or at least give you ideas

Is the answer

9? because in a 4x4 bow, you only need 4 (I've done it), so maybe you could do...

4x4 = 4.

so, 9x9 = 9?

[Guest]

nope not 9 =), turns out i had the number wrong on the 9x9 so now I see no relation between it and the 4x4 so just ignore that hint =P

[Guest]

I googled it and found this:

The inverse of this—the fewest givens that render a solution unique—is an unsolved problem, although the lowest number yet found for the standard variation without a symmetry constraint is 17, a number of which have been found by Japanese puzzle enthusiasts, and 18 with the givens in rotationally symmetric cells.

But, I also found this:

Someone tried to prove that it's indeed necessary that there are at least 17 givens. I don't know whether he succeeded or not, since I didn't really check the proof..

http://www3.sympatico.ca/georg.josephs/Sud...Calculation.htm