1 Move through the puzzle recording only the binaries in R,S,C (Rows, Squares, Columns). Binary: the only two possible placements in a R,S,C.

2 Look for singles in a R,S,C. A single possibility is your answer.

3 When you find a correct number and fill it in, erase the corresponding number in R,S,C. Then rebalance binaries in R,S,C.

4 Eventually, the undetermined squares will reduce to binaries within R,S,C.

5 If stuck, move through each row in sequence looking for at least two possible placements of each number that has not yet been determined; then repeat the process by column, then repeat the process by box. Where there is only one of a given number remaining in the R,S,C, that is the correct number.

Helpful Hints

1 All 9 - a number must work in all 9 locations within the puzzle or it is misplaced

2 Binary Pairs- one of the two binary numbers must be used in its R,S,C

3 Choice - There are no choices in Sudoku, all number placements are dictated. If you made a choice, you probably made a mistake!

4 Binary possible placement - The binary pairs in a row or column within a box dictate the actual placement of one of its numbers in an adjacent R,S,C.

5 Rushing, Guessing - no rushing or guessing; put the puzzle down, when you come back you will see other possibilities

6 Square check - if the number you wish to place in a row is already somewhere else in the square, it cannot go there