OK, more than a puzzle, this is an interesting mathematical oddity. You may want to explain how come, though.
Take any three-digit number (e.g.: 413).
Repeat the digits once more (e.g.: 413413).
Divide the resulting number by 7 (e.g.: 59059).
Divide the result by 11 (e.g.: 5369).
Divide the result by 13 (e.g.: 413).
Oddity number one: dividing succesively by 7, 11, and 13, results in an integer (or, in other words, no remainder), no matter with what number you start.
Oddity number two: you always get your original number back..
Hilmar.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
