## Conundrums

#### Coin and paper conundrum

Can you pass a 50 cent coin through a 10 cent coin-sized hole in a piece of paper without tearing the paper?

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## Explore more Conundrums

#### Exactly half?

Thursday, 23 October 2008 250K

You have a perfectly cylindrical glass filled with water. Without any kind of measuring device, how can you empty the glass so it is exactly half full?

#### Think outside the box

Monday, 8 September 2008 283K

Can you connect all nine dots by drawing four straight lines without lifting your pencil?

#### A Missing Thing

Wednesday, 16 July 2008 224K

What is it about this paragraph that is so unusual? At first, it looks totally normal, but it isn't! Focusing your curious mind will bring its odd quality to light.

#### Guess the shape

Tuesday, 17 June 2008 278K

This shape is the first in a series of nine. Can you guess the next shape?

#### Tie the Knot

Thursday, 28 June 2007 230K

Here's a challenge that really can be done! Pick a piece of rope and tie a knot without letting go of either end.

#### Full empty full

Thursday, 14 June 2007 277K

Line up six glasses. Fill the first three. Now move only one glass so they alternate full, empty, full. It can be done!

#### Free the note

Thursday, 31 May 2007 287K

Stack four 20c coins on top of a note on top of a bottle. Using only one, straight index finger, remove the note without disturbing the coins. It can be done!

#### Two Candle Riddle

Thursday, 5 April 2007 282K

A candle flame consumes oxygen and produces water vapour and carbon dioxide. Carbon dioxide is heavier than air. But cover two candles with a jar and the taller one goes out first. Why?

#### Rope around the world

Thursday, 15 February 2007 422K

You have a piece of rope that just fits around the Earth. If you put 1 metre high sticks right around the equator and lay the rope on top, how much longer does the rope need to be to make ends meet?

#### Flip the triangle

Thursday, 1 February 2007 162K

Can you turn this triangle upside down by moving only three of the coins?

#### Manhole covers

Thursday, 25 January 2007 267K

Manhole covers come in many shapes. For safety however, why is a circle the best shape for covering deep holes?

#### Glass Half Full

Thursday, 11 January 2007 177K

At precisely what time was the glass exactly half full with bacteria?

#### The missing dollar

Thursday, 28 December 2006 203K

Three friends contribute each towards a pizza. They give the delivery driver a tip and get change each. But something weird has happened! Where is the missing dollar?

#### Egg Pickle

Thursday, 14 December 2006 270K

If you have a hardboiled and a raw egg how can you tell them apart without cracking either egg's shell?

#### Tricky intersection

Thursday, 30 November 2006 135K

Four cars are stopped at a four-way intersection. At the same time and at the same speed, they all drive forward and continue their journeys without colliding. How is this possible?