Use the digits 1 to 9 exactly once each to build a perfect square
Take the nine digits 1 through 9, each used exactly once, and arrange them into a single nine-digit number that is also a perfect square. There are several possible answers. What is the smallest such number you can make, and what is the largest?
Reveal the answer
The smallest is 139,854,276 (the square of 11,826), and the largest is 923,187,456 (the square of 30,384). Henry Dudeney published this as 'Digital Square Numbers' in Amusements in Mathematics (1917).
— Henry Ernest Dudeney, Amusements in Mathematics — Thomas Nelson & Sons, 1917
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