4

MATHEMATICAL CIRCLE S (RUSSIA N EXPERIENCE )

Problem 23 . I s it possibl e t o arrang e si x long round pencil s s o that eac h o f the m

touches al l th e others ?

Problem 24 . Usin g scissors, cu t a hole i n a sheet o f ordinary pape r (say , th e siz e

of this page ) throug h whic h a n elephan t ca n pass .

Problem 25 . Te n coins are arranged a s shown i n Figure 5 . Wha t i s the minimu m

number o f coins we must remov e so that n o three o f the remainin g coin s li e on th e

vertices o f an equilatera l triangle ?

FIGURE 5