# Brainteaser Answers – Issue 8, 2007

In each issue of the Automation Notebook we feature a section of brainteasers. These are the brainteaser answers from Issue 8, 2007  of the Automation Notebook. The brainteaser questions are repeated in black. The answers to the brainteaser questions are highlighted in red with explanations. You can view the brainteasers from Issue 8, 2007 without the answers here: http://library.automationdirect.com/brainteasers-issue-8-2007/

## 1.What’s the largest US coin that can pass through a hole cut in a piece of paper that is exactly this size without tearing the paper?

This circle can be re-created by cutting a hole the size of a nickel (0.835 inches in diameter) in a piece of paper.

Answer: All of the types of US coins currently in circulation will fit through the hole.  Simply fold the paper as shown, allowing the hole to form a long slot.  This slot will open to be much longer than the diameter of the hole.

## 2.Can you grasp a handkerchief by two opposing corners and tie a single knot in the center without letting go of either end?

Answer: Fold your arms BEFORE you pick up the handkerchief. When you uncross your arms, the knot will form.

3. The machine shop in Puzlandia currently has 22 machine tools on the shop floor arranged as shown below (top view). The shop foreman wants to re-arrange the machines into rows of four to increase the efficiency of the shop. How many rows of four can you provide given that he will only allow you to move six of the machines? He claims he can achieve 19 rows of four. Can you find a way to re-position just six of the machines and get 20 rows of four machines?

Answer: The graphics below show the solution to this problem.