New Scientist Enigma 871 – Pandigitals
by Colin Singleton
From Issue #2026, 20th April 1996 [link]
Uncle Joe had written the digits 0 to 9 on ten cards, some red, the others blue, one digit per card. “Now boys,” he said, “you have to arrange the red cards on the table to form a number, and divide the blue cards into two groups to form two separate numbers. The ‘red’ number must be the product of the ‘blue’ numbers.”
“Like this?” said Tom. “Or this?” said Dick. “Or this?” said Harry.
“All different, and all correct!” replied Uncle Joe.
Only Tom had included a single-digit number in his arrangement. What was Harry’s ‘red’ number?