From Latin squares to a Tokyo magazine to the world's newspapers — how a number-placement puzzle became a global habit.
Sudoku feels timeless, which is usually a sign that a thing is older than people assume. The modern grid is roughly forty years old; the mathematics underneath it is closer to two hundred.
The path between those two is more accidental than anyone expects.
It starts with Latin squares
A Latin square is an n-by-n grid filled with n symbols so that each appears once per row and once per column. Mathematicians studied them long before anyone thought to make a puzzle out of one.
Sudoku is a Latin square with an extra constraint: each 3×3 box must also contain every digit. That single addition is what makes the puzzle interesting rather than trivial.
An American magazine, then a Japanese one
A number-placement puzzle appeared in a US magazine in the late 1970s under a different name and did not catch on. It was picked up in Japan a few years later, given the name Sudoku — roughly "single number" — and became genuinely popular there.
The name stuck, which is why an American-invented puzzle is universally known by its Japanese name.
The newspaper explosion
In the mid-2000s Sudoku began appearing in British and then American newspapers, and within about two years it was a daily feature in most of them.
What made it spread was not difficulty but format: a puzzle that needs no language, no equipment and no explanation travels very well.