Lesson 3

Make a notation at the end of the row or column the list of numbers missing.

You can only put the notation numbers in the 2 squares if they are in the same box.

Only put notation numbers at the top of the square if there are only 2 possibilities in that box.
If they are not in the same box, then do not put the two numbers in the squares.

So in this example, you can put the 5 and 8 in the two blue squares because they are in the same box. 

If you look two rows up from the blue squares there is a row with 5,8 beside it also.
The 6 and 4 have those two squares locked up.  The 5 and 8 go into the other two squares.
You cannot put the 5 and 8 notation numbers at the top of those squares because they are not in the same box. 

Also you cannot put the 6 and 8 in the right column because they are in different boxes.

NEXT LESSON 4