Magic Squares: 3×3

Magic Squares: 3×3

Magic Squares: Odd

The magic square, according to Chinese legend, was first constructed on the back of a turtle and is called the Lo Shu magic square, the only order of numbers in a 3×3 grid in which they all add up to 15.

By contrast, when there are 4 rows and columns, there are 880 different ways to lay out the numbers in a magic square. Constructing a magic square is different if there are an odd number of rows and columns than an even number. Let’s get started making your own!

Materials:

• Paper
• Pen or pencil
• Ruler or straight-edge

Instructions:

• Put 1 in the middle of the top row and keep placing numbers diagonally, according to the following rules
• Put the next number, 2, diagonally, up one square to the right
• When a number falls outside the grid to the right diagonally above a column, wrap it around and put in the square at the bottom of that column. 2, for example, instead of going in a square above the upper right corner square, will go in the bottom right corner of the 3×3 grid.
• When a number falls outside the grid to the right of a row, wrap it around and put it in the square on the left end of that row, thus 3, if put diagonally from 2 would be to the right of the middle row, wraps around to be placed in the left most square in the middle row
• If a cell already has a number in it, put the number below the last number place. Thus 4, which can’t be place diagonally from 3 because there is already a 1 there, is placed below the 3, in the bottom left corner.
• Continue through number 9.

What Should Happen?

• When there is a number in every box, they should be laid out: first row – 8,1,6
• Second row – 3, 5, 7
• Third row – 4, 9, 2
• Each row, column and the three-number diagonals should add up to 15.
• These rules should work for all odd-numbered magic squares.
• Click here to see an animation of how a 3×3 magic square is constructed and how the rules apply.
• This is called the Siamese method of constructing a magic square, after a French ambassador to Siam (now Thailand), De La Loubere, who brought it back to France from Siam.

Why Is This Useful?

Most Sudoku puzzles are 9×9 grids, made up of 3×3 grids. Invented by Howard Garns and first published in May 1979, Sudoku puzzles are a variation of Latin squares, in which no number or symbol in a grid repeats. Players are challenged to put a number from 1 to 9 in each column such that it does not repeat within any 3×3 box or in any row or column. Two mathematicians, Bertram Felgenhauer and Frazer Jarvis estimated that there are 6 sextillion combinations of Sudoku puzzles.

Carol Covin, Granny-Guru

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers”

http://newgrandmas.com

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Filed in: education • Playtime Tags: magic squares