Lesson 2 · Read the board
Rows, Columns and Boxes
See how every cell belongs to three connected groups at the same time.
See the logic move
Use Next to reveal each reason. On the final step, tap the highlighted cell to complete the move yourself.
Step 1 of 3
One row
The blue band is the selected cell's row.
Select an empty cell to see its legal candidates and why the other digits are blocked.
- 1
Focus: Start here. This is the cell or area being investigated. R5C5.
- 2
Relevant cells: These cells share the row, column, or box used by this step. Row 5.
What the board is showing
Explain it simply
A cell has three neighbourhoods: its horizontal row, vertical column, and small box.
Step by step
- Find the cell's row.
- Trace its column.
- Locate its 3x3 box.
- Combine the information from all three.
From demonstration to independent solving
Prove the move yourself
What you should be able to do
Recognise the three units attached to a selected cell and switch between them without scanning the whole board.
Read the exact board evidence
R5C5 sits in row 5, column 5 and the centre box. A 7 at R5C2 blocks 7 horizontally, a 7 at R2C5 blocks it vertically, and a 7 anywhere from R4C4 to R6C6 blocks it through the box.
When the logic is strong enough
Every candidate decision must be explainable by one or more of these exact units. A distant number outside all three has no effect on the selected cell.
Train the pattern without guessing
Tap a corner cell, an edge cell and a centre cell. For each one, trace its nine-cell row, nine-cell column and nine-cell box before checking candidates.
Quick check: How many rows, columns, and boxes does one cell belong to?
One row, one column, and one 3x3 box.
Turn logic into skill