How many?

Metres

The metre, or meter, is the base unit of length in the International System of Units (SI). The SI unit symbol is m. The metre is currently defined as the length of the path travelled by light in a vacuum in 1/299,792,458 of a second. The current world record for running 100 metres is 9.58 seconds, set by Usain Bolt in 2009.

Inches

The inch is a unit of length in the British imperial and the United States customary systems of measurement. Since the adoption of the international yard during the 1950s and 1960s it has been based on the metric system and defined as exactly 25.4 mm. The standard size pencil that you may see in schools and offices is 7 inches long.