The 10-Minute Medium: A Speed-Runner's Guide to Intermediate Sudoku

For many players, a medium Sudoku puzzle is a comfortable challenge—a 15-20 minute affair. But what separates a casual solver from a speed-runner is efficiency. Breaking the 10-minute barrier isn't about raw intelligence; it's about having a refined process and a sharp eye for the most common patterns. This guide will give you the tools and mindset to turn your medium solves into high-speed triumphs.

Phase 1: The Initial Blitz (Seconds 0-60)

The first minute of your solve is the most critical for setting the pace. Your goal is to fill every "obvious" number on the grid without hesitation. This phase should be almost automatic.

The Number-by-Number Scan

Don't randomly hunt for singles. Adopt a systematic approach. Start with the number '1'. Scan the entire grid using cross-hatching to find where any '1's must go. If it's not immediately obvious, move to '2'. Then '3', and so on, all the way to '9'. This systematic pass ensures you don't miss any low-hanging fruit and gives you a complete overview of the grid's state. After this first pass, you should have 5-10 new numbers on the board.

Phase 2: Targeted Pencil-Marking (Minutes 1-4)

Here's a key speed-solving secret: **do not pencil-mark the entire grid**. It's slow and clutters your view, hiding the very patterns you need to find. Instead, be surgical.

Focus on Crowded Areas

After your initial blitz, identify the most constrained units (a 3x3 box, row, or column with 5 or 6 numbers already filled). Now, *only* pencil in the candidates for the empty cells in *those* units. This is far more efficient. A crowded box with only 3 empty cells is much more likely to reveal a Hidden Single or a Locked Candidate pair than a wide-open box with 7 empty cells.

The Key Patterns for Medium Speed

To solve in under 10 minutes, you need to spot these two patterns almost instantly.

1. Hidden Singles

This is your primary weapon on medium puzzles. After your targeted pencil-marking, scan the unit you just marked up. Ask, "In this box, where can the number '7' go?" If it can only go in one cell, you've found a Hidden Single. This must become an automatic, reflexive action.

2. Locked Candidates (Pointing & Claiming)

This is your cleanup tool. Spotting that all candidates for a '4' in a box are in the same row allows you to remove '4's from the rest of that row. This doesn't solve a cell directly, but it cleans your candidate list, which in turn reveals the next Hidden Single. Learning to see these relationships quickly is vital. Read more on our Sudoku Tips page.

The path to a sub-10-minute medium solve is about turning conscious effort into unconscious skill. It's about building a smooth, repeatable workflow that minimizes wasted time and maximizes your brain's incredible pattern-recognition ability. Practice the systematic scan, use targeted pencil marks, and master the "Place & Clean" rule, and you'll be breaking your own personal bests in no time.