In this puzzle, there were four sevens (circled blue) in the UL and LL boxes.
They are in the same columns and have those locked up. Therefore the ML box had to have
the seven in the middle column and in the lower square (red color) because of the
seven over in MR box.
Make notations in the side if there are just 1,2, or3 squares empty
in a row or column.
In the third row down, the numbers missing are 2, 6, and 8.
If a row is missing only 2 or three numbers, then look
in the opposite direction from each square to see if all but one number
is there. So if you look at the red square, there is
a 2 and 6 below it and therefore the 8 must go in that square.
That leaves the 2 and 6 in that row and with the 2 being below the
right empty square, then the 2 goes in the left empty square and the 6
in the right empty square of that third row.
Next Lesson 7
