Pointing and box/line

When all the spots for a digit in a box sit in one row or column, that line gets its digit from the box. So the rest of the line can’t have it.

Clear 7 from the rest of the line.

Why it works

On the board above:

In box 5, the only spots for 7 are r4c4 and r4c6. They all sit in row 4.

Box 5 needs a 7, so its 7 will land somewhere in row 4.

Row 4 can only have one 7. So r4c3, outside the box, can’t be 7.

Pick a box and a digit
Look only at where that digit can still go inside the box.
Check if the spots line up
Two or three spots, all in one row or all in one column.
Clear the rest of that line
Remove the digit from that row or column outside the box.
Then try it the other way
If a row’s spots for a digit all sit inside one box, clear the rest of that box.

Real boards from the solver, with every pencil mark filled in. Spot it, then use it, then find it cold.

Loading the boards…

Each of these needs pointing or box/line to finish. It opens in the player.

For each box, ask which digits are stuck on one line. It is quick once you get the habit.

A pointing pair often leaves a single behind it. Look for one right after you clear.