THE ARTFUL SCHOOLBOYS
At a certain school were four long dormitories, built in the form of a square, in which thirty-two boys occupied beds, as shown by matches in [Fig. 17].
Fig. 17.
By this arrangement the master, in going his rounds at night, counted twelve boys in each corridor. One night four boys absented themselves from the school, and the remaining boys rearranged themselves in such a manner that the master was still able to count twelve boys in each corridor, and the absence of their four comrades was not noticed. How they did it is shown in [Fig. 18].
Fig. 18.
The four absentees returned on the following night, accompanied by four friends; but the master was unable to notice the addition, for he again counted twelve boys in each dormitory. The new arrangement was as [Fig. 19].
Fig. 19.
There were now thirty-six boys sleeping in the dormitories, and next night they were joined by four more, which brought the number up to forty, and yet the master 65 only counted twelve in each dormitory on his rounds that night. How the new distribution was made is shown in [Fig. 20].
Fig. 20.
Next night four more chums popped in for a snooze, making a total of forty-four, and again the master was bamboozled by the following readjustment ([Fig. 21]).
Fig. 21.
History is silent upon the subject of the arrangement at the breakfast-tables.
The proper way to present this puzzle to your friends is to lay forty-four matches on the table, and after showing the initial arrangement, allow them to work the rest out for themselves.