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Big and Small Numbers

People are great at using and understanding numbers between one and ten but scientists often need to use much larger quantities.

  • The speed of light is 300,000,000 metres per second.
  • The distance to the moon is 384,467 kilometres.
  • There are usually between 10,000,000 and 20,000,000 sperm per millilitre of human sperm.

Big numbers like these can get confusing.

  • One thousand 1,000
  • One million 1,000,000
  • One billion 1,000,000,000
  • One trillion 1,000,000,000,000

Some of these numbers are truly huge, think about them as measures of time:

  • One thousand seconds is nearly 17 minutes
  • One million seconds is 11½ days
  • One billion seconds is nearly 32 years
  • One trillion seconds is nearly 31,710 years

Things can get worse, there are around 8,360,000,000,000,000,000,000,000 molecules in a cup of tea!

Going to the other extreme very small numbers are used by scientists just as often.

  • These marine diatoms (seen here through a microscope) range in size from ten to 150 millionths of a metre. That is from 0.00001m to 0.00015m.
  • The wavelength of the blue light coming from this image is about 450 nanometres (nm) - 0.00000045m.

  Scientific notation is the answer.

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