BrightKidz Library
Subjects
An animal sudoku grid part way through being solved A four by four grid with thicker lines splitting it into four blocks of four squares. Twelve of the sixteen squares already hold an animal and four are empty, one in every row. The empty square in the top row is outlined with a dashed line to show it is the one being worked out. The four animals of the puzzle are shown as large round tokens either side of the grid: a lion and a monkey on the left, a zebra and an elephant on the right.

Animal Sudoku Challenge

About 8 minutes

Sudoku has nothing to do with adding up. You never do a sum. It is a puzzle about where things cannot go — and once enough places are ruled out, only one possibility is left, and that one must be right.

This version uses animals instead of numbers, which changes nothing at all.

The Rules

Our grid is four squares across and four squares down, split into four smaller boxes of 2 × 2. Four animals go in it: Lion, Monkey, Zebra and Elephant.

Four animals, four rows, four columns, four boxes. The number of animals always matches the size of the grid — that is what makes the puzzle possible.

The Puzzle

To keep the grid narrow enough to read, each animal is written as its first letter:

L = Lion · M = Monkey · Z = Zebra · E = Elephant

Four squares are empty. Copy the grid onto paper and fill them in.

The animal sudoku puzzle A four by four grid divided into four boxes of two by two. L stands for Lion, M for Monkey, Z for Zebra and E for Elephant. Four squares hold a question mark and are the ones to fill in: row one column two, row two column three, row three column four, and row four column one. L ? Z E Z E ? M M L E ? ? Z M L
Four squares are empty. Every row, every column and every 2 x 2 box needs all four animals.

The thick lines mark out the four boxes. Each of those 2 x 2 blocks needs all four animals too, exactly like a row or a column does.

How to Start

Take Row 1. It already has L, Z and E, so the missing one has to be M — there is nothing else left. That is the easiest kind of move there is, and it is worth hunting for before anything cleverer.

Now Row 4, which has Z, M and L. The gap must be E.

Rows 2 and 3 work the same way. Every row here is missing exactly one animal, so you never need the columns or the boxes to solve it — but check them anyway when you finish. If a column has the same animal twice, something has gone wrong.

Row 2 reads Z, E, ?, M. Which animal belongs in the gap?

The Answer

The animal sudoku, solved The same four by four grid with every square filled. Row one reads L M Z E, row two Z E L M, row three M L E Z, row four E Z M L. The four squares that were blank are shaded. L M Z E Z E L M M L E Z E Z M L
The four shaded squares are the ones that were blank.

Check a column: column 1 reads L, Z, M, E — all four, no repeats. Check the top-left box: L, M, Z, E. All four again. Every row, every column and every box passes.

Tips for Bigger Sudokus

A full-size sudoku is nine across with nine digits and boxes of 3 × 3. The grid is bigger; the reasoning is exactly what you just did.