Think of a Number - Series 5

A 6 part series with Johnny Ball. Johnny bounces back with some lighthearted explorations into numbers and science. This week Johnny gets thrown off balance by two junior judo champions, but realising the gravity of the situation, recovers sufficiently to take a bicycle ride on a tightrope. Does he fall off ? Weight and see! Meanwhile - weigh this one up. A half is a third of it... what is it ?

Watch Johnny spring through sand, cement and sponge cakes and discover new angles to pool playing.

This week Johnny Ball airs his views on Plain Planes and Flights of Fancy with the aid of paper darts, boomerangs, kites and the only model jet aircraft in the world.

Johnny takes off his waistcoat without removing his jacket and spins his way through maps and mazes, helped by a robot mouse. So if you're knot amused, at least you'll be amazed.

Johnny whistles for the thistle sifter, finds out how a turtle draws and even meets a computer that talks back. So, in a few words - sag a teat in front of the belly.

This week, the last of the series, it's Think of a Number and Beat it! Johnny discovers that hitting things together goes down with a bang, crash, wobble and bonk - as well as a laugh. So if the mood strikes you-hit that button and watch out!