MathDB
TOT 322 1992 Spring O J3 coins in a one-layer box

Source:

June 9, 2024
combinatoricscombinatorial geometry

Problem Statement

A numismatist Fred has some coins. A diameter of any coin is no more than 1010 cm. All the coins are contained in a one-layer box of dimensions 3030 cm by 7070 cm. He is presented with a new coin. Its diameter is 2525 cm. Prove that it is possible to put all the coins in a one-layer box of dimensions 5555 cm by 5555 cm.
(Fedja Nazarov, St Petersburg)