Henry Ernest Dudeney/Puzzles and Curious Problems/250 - Adjusting the Counters

by : $250$

 * Adjusting the Counters
 * Place $25$ counters in a square in the order shown.


 * Dudeney-Puzzles-and-Curious-Problems-250.png


 * Then it is a good puzzle to put them all into regular order so that the first line reads $1 \ 2 \ 3 \ 4 \ 5$, and the second $6 \ 7 \ 8 \ 9 \ 10$,
 * and so on to the end, by taking up one counter in each hand and making them change places.


 * The puzzle is to determine the fewest possible exchanges in which this can be done.