Platon Sudoku · Sudoku Study
Hidden Single · Step-by-step example A digit has only one possible cell in a row, column, or box. The cell may still show other candidates. Put the digit in the only remaining cell of that region.
This course is adapted from Platon Sudoku App. Read the complete example here, then continue learning and practising in the app.
View on Google Play ↗ Step-by-step example Recognize the pattern A digit has only one possible cell in a row, column, or box. The cell may still show other candidates.
How to find it Choose one digit and scan a box, row, or column. Rule out cells that see an already placed copy of that digit.
What it allows Put the digit in the only remaining cell of that region.
Avoid the mix-up A naked single has one candidate in a cell. A hidden single has one place for a digit in a region. Check every cell in that region before placing it.
Step-by-step example · Box This example starts from a saved intermediate position. Its candidates include earlier logical eliminations; they are not fresh automatic notes.
Blue: evidence. Green: conclusion. Crossed-out digits: eliminated candidates. R1C1 means row 1, column 1.
Step 1 · Find 7 in box 4 Focus on 7. Where can it still go in box 4?
Focus on 7. Where can it still go in box 4? Step 2 · Rule out the other positions row 6, column 3 already contain 7. The crossed positions cannot contain 7, leaving only R5C1 in box 4.
row 6, column 3 already contain 7. The crossed positions cannot contain 7, leaving only R5C1 in box 4. Step 3 · Place 7 R5C1 is the only place for 7 in box 4.
R5C1 is the only place for 7 in box 4. What it allows R5C1 is the only place for 7 in box 4.
Hidden Single · Put the digit in the only remaining cell of that region. Step-by-step example · Row This example starts from a saved intermediate position. Its candidates include earlier logical eliminations; they are not fresh automatic notes.
Blue: evidence. Green: conclusion. Crossed-out digits: eliminated candidates. R1C1 means row 1, column 1.
Step 1 · Find 3 in row 6 Focus on 3. Where can it still go in row 6?
Focus on 3. Where can it still go in row 6? Step 2 · Rule out the other positions column 7, column 6, column 9 already contain 3. The crossed positions cannot contain 3, leaving only R6C8 in row 6.
column 7, column 6, column 9 already contain 3. The crossed positions cannot contain 3, leaving only R6C8 in row 6. Step 3 · Place 3 R6C8 is the only place for 3 in row 6.
R6C8 is the only place for 3 in row 6. What it allows R6C8 is the only place for 3 in row 6.
Hidden Single · Put the digit in the only remaining cell of that region. Step-by-step example · Column This example starts from a saved intermediate position. Its candidates include earlier logical eliminations; they are not fresh automatic notes.
Blue: evidence. Green: conclusion. Crossed-out digits: eliminated candidates. R1C1 means row 1, column 1.
Step 1 · Find 2 in column 6 Focus on 2. Where can it still go in column 6?
Focus on 2. Where can it still go in column 6? Step 2 · Rule out the other positions box 2, box 5, row 8, row 9 already contain 2. The crossed positions cannot contain 2, leaving only R7C6 in column 6.
box 2, box 5, row 8, row 9 already contain 2. The crossed positions cannot contain 2, leaving only R7C6 in column 6. Step 3 · Place 2 R7C6 is the only place for 2 in column 6.
R7C6 is the only place for 2 in column 6. What it allows R7C6 is the only place for 2 in column 6.
Hidden Single · Put the digit in the only remaining cell of that region. Practice This course is adapted from Platon Sudoku App. Read the complete example here, then continue learning and practising in the app.
View on Google Play ↗ 
