Is 5×5 Shikaku good for beginners?

Yes! 5×5 is the perfect starting point. Small enough to solve in 2-3 minutes, but challenging enough to teach core techniques like corner-first and factor decomposition.

How many rectangles are in a 5×5 Shikaku puzzle?

It varies, but typically 6-10 rectangles. The number depends on how the grid is partitioned — larger rectangles mean fewer total pieces.

What's the hardest part of 5×5 Shikaku?

The middle cells. Edges and corners are constrained, but center cells have more possible rectangle orientations. Use chain reasoning to narrow down center placements.

Shikaku 5×5 — The Perfect Starting Point

A 5×5 Shikaku grid has 25 cells — small enough to solve in 2-3 minutes, but challenging enough to teach you every core technique. This guide covers specific 5×5 strategies and walks through 3 complete puzzles.

▶ Play 5×5 Shikaku Now

Why 5×5 is Perfect for Beginners

25 cells — manageable mental load, no need for paper notes
6-10 rectangles — enough variety to practice different techniques
2-3 minute solve time — quick feedback loop for learning
All numbers ≤ 25 — factor pairs are easy to compute mentally

5×5-Specific Strategies

The "25 Check"

Before placing anything, add up all the numbers on the grid. They must sum to exactly 25 (the total cells). If they don't, the puzzle is broken.

Corner Priority

In a 5×5 grid, corners are extra constrained. A "2" in a corner has only one possible shape. A "3" in a corner has only two. Always start here.

Edge Numbers ≥ 5

If a number ≥ 5 is on an edge, it must extend along that edge (1×N or N×1). A "6" on the top row can only be 1×6 — but the grid is only 5 wide, so it must wrap or the puzzle is invalid. This means large edge numbers are very constrained.

Worked Example 1: Easy 5×5

┌───┬───┬───┬───┬───┐
│ 2 │   │ 3 │   │ 1 │
├───┼───┼───┼───┼───┤
│   │ 4 │   │ 2 │   │
├───┼───┼───┼───┼───┤
│ 3 │   │   │   │ 2 │
├───┼───┼───┼───┼───┤
│   │ 2 │   │ 3 │   │
├───┼───┼───┼───┼───┤
│ 1 │   │ 2 │   │ 1 │
└───┴───┴───┴───┴───┘

1Mark all "1" cells. (0,4), (4,0), and (4,4) are 1×1 rectangles. Done.

2Corner "2" at (0,0). Can go right (0,0)-(0,1) or down (0,0)-(1,0). Try right: 1×2 horizontal.

3"3" at (0,2). Top row, so try 1×3 horizontal: (0,2)-(0,4). But (0,4) is already a "1". So try 3×1 vertical: (0,2)-(2,2).

4"4" at (1,1). Could be 1×4, 2×2, or 4×1. A 2×2 square (1,1)-(2,2) fits. But (2,2) is taken by the "3". So try 1×4 horizontal: (1,1)-(1,4). But (1,3) has a "2". So try 4×1 vertical: (1,1)-(4,1). But (3,1) has a "2". Try 2×2 at (1,1)-(2,2) — no, (2,2) is taken. The only option: 1×4 right doesn't work, 4×1 down doesn't work, 2×2 conflicts. Go back and reconsider step 2.

5Backtrack: "2" at (0,0) goes down instead: (0,0)-(1,0). Now "4" at (1,1) can be 2×2: (1,1)-(2,2). "3" at (0,2) goes right: (0,2)-(0,4). Continue filling...

Worked Example 2: Medium 5×5

This puzzle has a "6" in the center — the trickiest number in 5×5 because it can be 1×6 (too wide), 2×3, 3×2, or 6×1 (too tall). Only 2×3 and 3×2 fit.

┌───┬───┬───┬───┬───┐
│ 3 │   │   │ 2 │   │
├───┼───┼───┼───┼───┤
│   │   │ 6 │   │   │
├───┼───┼───┼───┼───┤
│   │ 2 │   │   │ 3 │
├───┼───┼───┼───┼───┤
│ 2 │   │   │   │   │
├───┼───┼───┼───┼───┤
│   │ 1 │   │ 2 │   │
└───┴───┴───┴───┴───┘

The "6" at (1,2) must be 2×3 or 3×2. Check which fits: 2×3 horizontal (1,1)-(2,3) works. 3×2 vertical (0,2)-(2,3) also works. Use surrounding numbers to decide — the "2" at (0,3) and "3" at (2,4) constrain the space.

Progressing to Larger Grids

Once you can solve 5×5 puzzles consistently (90%+ success rate), try 6×6. The same techniques apply, but you'll need to manage more numbers and larger factor lists.