Think of a Number - Season 3

First aired: 9/10/1980 6 episodes

Episodes

1. Wheels Within Wheels

Aired: 9/10/1980

The first of six programmes with Johnny Ball. Round wheels, not-so-round wheels, oval wheels, big wheels, little wheels; and a chance to see how you can go backwards while going forwards! Plus an eccentric bike and the newest engine that goes straight round the world. Meanwhile, see if you can get around to solving this one. Cut up a circle into 22 parts using only six straight lines.

2. The Science of See-through Sand

Aired: 9/17/1980

He cooks, looks, hits, breaks and bends... glass. See some glass over 3,000 years old, a teardrop that goes with a bang and a singer who has a smashing time. Meanwhile, see if you can see through this one. Divide a clock face with two straight lines so that the numbers in each part are equal.

3. No Cockles, Just Muscles, Alive Alive Oh

Aired: 9/24/1980

Squeezing muscles, waving muscles, levering muscles, springing muscles and jumping muscles. He'll be in deep water seeing how Archimedes showed his muscles, how to travel first class and still keep a balance and how to keep a camera steady when you're all over the place. Meanwhile, flex your brain on this one: A round-the-world cyclist has travelled 15,951 kilometres. How many kilometres must he travel before his speedometer again shows a number which reads the same backwards ?

4. Elementarianisticalizationableism... or it's elemental when it's on the table

Aired: 10/1/1980

Atomic elements, lit up elements, man-made elements and elements that melt in your hand. See how two people become the salt of the earth, the spoon that won't stir your cocoa and a machine that knows its place - underground. Meanwhile, try to iron out this one - hope it's not too 'Boron'. Three matches make four - how ? You mustn't break them.

5. Hello Listeners

Aired: 10/8/1980

Listening to loud sounds, soft sounds, old sounds and new sounds. Recording some of the first sounds. Investigating drums in the head. Transmitting sounds with a milk bottle and asking a machine to do the talking. Meanwhile sort this out 'ear: A record costs £2 plus half its price. How much does it cost ?

6. 2D or not 2D, That is the Question

Aired: 10/15/1980

Doubling dimension, flexing flexagons and perceiving perspective. See the impossible triangle, two dimensional people who live in flats and the latest development in photography that is far from flat. Meanwhile weigh this up: If you put three quarters of a cake on one side of a scale and half of a cake and a 250 gram weight on the other, it balances. What does the whole cake weigh ?