Hexadoku Medium Online: Hidden Singles in the 16-Symbol Grid
Hexadoku Medium is an intermediate 16×16 logic puzzle played with sixteen symbols — digits 1–9 and letters A through G — across 256 cells. Medium puzzles begin with 92–105 starting clues. At this level, naked singles alone no longer solve the grid: players must identify hidden singles and apply pointing pairs across the full width and height of the 16-row board. Play free at SudokuPro — no registration required.
Characteristics of Hexadoku Medium
- Grid: 16×16 = 256 cells
- Symbol pool: Digits 1–9 plus letters A–G
- Starting clues: 92–105
- Logic required: Hidden singles, pointing pairs, cross-unit elimination
- Typical solve time: 50–90 minutes
- Best for: Solvers who have completed Hexadoku Easy and want a genuine logic workout
Medium is the first level where pencil marks become genuinely useful. Many cells will still have several possible candidates, so progress comes from finding where a symbol can go — not only where a cell can be filled.
Solving Strategies for Hexadoku Medium
Strategy 1: Hidden Singles
A hidden single is a cell where a particular symbol can appear in only one position within a row, column, or 4×4 box, even though that cell may still have multiple candidates.
In Hexadoku Medium, the reduced clue count means many cells cannot be solved through naked elimination alone. Instead, scan each unit for symbols that are blocked everywhere except one cell. With sixteen symbols to track across sixteen positions, hidden singles become one of the most reliable sources of progress.
Strategy 2: Pointing Pairs
A pointing pair occurs when all candidates for a symbol inside a 4×4 box are confined to a single row or column. If that happens, the symbol can be eliminated from the rest of that row or column outside the box.
Hexadoku's 16-column width gives this technique extra leverage. A single pointing pair can remove candidates from up to twelve other cells and may immediately create hidden singles in neighboring boxes.
Strategy 3: Cross-Unit Elimination
Work through the sixteen symbols one at a time. For each symbol, mark every row and column where it already appears. Then inspect the boxes where that symbol is still missing. If only one unblocked cell remains in a box, place the symbol there.
This cross-unit sweep is the most efficient way to combine hidden singles and pointing-pair logic. At Medium difficulty, one full sweep through all symbols can often create 10–20 placements or eliminations.
Next Steps
Advance to Hexadoku Hard, where naked pairs, hidden pairs, and locked candidates become necessary. Return to Hexadoku Easy to build confidence, or visit the Hexadoku hub for the full level overview. The How to Play Sudoku guide expands on hidden singles and pointing pairs with interactive walkthroughs.