Pencil in jacket buttonhole

53

Pencil in jacket buttonhole

Take a pencil, make a groove in it near one of the ends, then tie a loop from the rope so that the length of the rope on the loop is less than twice the distance from the groove to the other end of the pencil (see Fig. 1). Now tie a loop to the pencil with the remaining ends of the rope, encircling the pencil along the groove, having first threaded the loop into the buttonhole of the jacket, and the pencil into the loop as shown in Fig. 2. The groove is needed so that the loop is rigidly attached to the pencil.

Now try, without untying the rope, without tearing it, without breaking the pencil, to remove the pencil from your jacket.

There is a little story connected with this task. In 1951, the remarkable Soviet mathematician, now a corresponding member of the USSR Academy of Sciences, I. R. Shafarovich gave his first course of lectures at Moscow State University. During the break, the students showed him this problem. Igor Rostislavovich tried one option, then another, but… the pencil remained on his jacket both during the next hour of the lecture and after it.

When Igor Rostislavovich appeared at his next lecture a few days later, the pencil continued to decorate his jacket. However, the lecture began with Shafarovich solemnly freeing himself from this decoration.

How will it work out for you?

Fig. 1.

Fig. 2.