⟩ What is the minimum no of coins of the same size that can be placed on a table so that each coin touches only three, others? All coins must lie flat on the table. What will be the arrangement of the coins?
I belive the answer is 20. 5 sets of four diamonds which when put together form a circle. Hard to eplain without a picture. The each daimond has no space in the middle. Two coins are touching three others and the other two coins are only touching two. But when the ends of these diamonds are put together each coin is touching only 3 others.
