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The Guardian - UK
The Guardian - UK
Science
Alex Bellos

Can you solve it? Are you smarter than a Japanese schoolchild?

The only maths you need to know is that the area of a rectangle is the length multiplied by the width.

Hello Guzzlers.

It is with huge pleasure that I introduce today’s puzzle, which is already a big deal in Japan. It’s called Menseki Meiro, or Area Maze, and I hope you find it as brilliant as I do.

Area Maze is the creation of Naoki Inaba, one of the world’s most prolific inventors of logic puzzles. He came up with Area Maze after being asked to come up with a puzzle by the head of a crammer school in Japan.

The puzzle is utterly simple to explain: find the missing value, which is denoted by a question mark highlighted in grey. The only mathematics you need to know is that the area of a rectangle is the length multiplied by the width.

Here’s what makes the puzzle genius: You are NOT allowed to use fractions in the solutions. If you were, you could write out lots of equations and solve them. Yuck, yuck, yuck. All Area Mazes can be solved using only whole numbers. Here’s a very simple one to get you going. If you need help with it scroll down.

area maze
Area Maze: starter. To print, click here.

Now you’ve got the hang of it, try these four. The first two are not too hard, the third requires a bit more thought - and the fourth may take you all day!

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Area Maze: 1. To print, click here.
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Area Maze: 2. To print, click here.
area
Area Maze: 3. To print, click here.
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Area Maze: 4. To print, click here.

Naoki Inaba has been devising puzzles since he was a teenager. He earns his living providing the Japanese media with well-known puzzles, like Sudoku, and also creating hundreds of new ones of his own. His website (in Japanese) has more than 400 original puzzles.

I asked him about Area Maze. “Calculating the areas of rectangles is not a new theme,” he said. “So I myself didn’t think I could make very interesting puzzles with it at first. Once I started making some Area Maze problems I hit upon some ideas about it one after another, and was able to make various problems – from easier ones to harder ones, and problems which need kind of inspiration to solve. Consequently, not only the children of the cram school but also many puzzle fans like it.”

In fact, it is so popular in Japan that now Area Maze problem books are published. Here’s a link to an Area Maze book on Amazon.jp, and you can also download this free Area Maze iPhone app.

naoki inaba
Naoki Inaba infront of a shelf of his Area Maze books. Photograph: Naoki Inaba

Ill be back later today to show you how to solve the more difficult puzzles.

Meanwhile, here’s how to solve the very first one.

The trick is to complete the large rectangle, as below. We know that the area A must be 20cm, since it is 4 x 5. Which means that A + the rectangle below it has area 20 + 16 = 36cm. This area is the same as the large rectangle on the left side. Since they share the same height, they must share the same width - so the missing value is 5cm.

area maze
Area Maze: starter solution

I post a puzzle here on a Monday every two weeks. If you like games you might be interested in LOOP, a new type of pool I devised that’s played on an elliptical table. You can also check me out on Twitter, Facebook, Google+ and my personal website.

If you know of any great puzzles that you would like me to set here, get in touch.

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