clara5218 wrote:hi davidpbrown, plse forgive me, im new at this game, but are you sure your pencil marks are correct in your grid? i see a 4 can be pencilled in at row 6 column 5 you only list 6,8 but i cant see why you cannot pencil in a four? is it because there are pencil marks for 4 in the r5c6 and r6c6? please explain why 4 should not be pencilled in at r6c5 - please dont see this as a criticism i am just trying to understand the rules of putting in pencil marks - cheers
He probably had a 4 before cleaning up the grid, but the reason he can't have a 4 in that position is because 6 and 8 can only be in columns 5 or 8, therefore since they must be in these columns 4 can't be.