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From Mega to Micro

  • Millimetre, milligram, millilitre;
  • megabyte, megatonne and megabucks;
  • microsecond and femtosecond,
  • a billion, a trillion.

What do they all mean?

Mega to Micro is all about those prefixes that appear in everyday news items as well as in technical reports. Also, we have included examples for distances.

The table deals with powers of 10 which also measures the number of digits in a number - the higher the power, the longer the number.


Power Size Name Prefix Symbol Metres example
1018 1,000,000,000,000,000,000 one quintillion exa E Light takes 100 years to travel this distance, to the star Arcturus
1015 1,000,000,000,000,000 one quadrillion peta P Distance to the "cloud" of comets 10 times as far away as the outermost planet, Pluto
1012 1,000,000,000,000 one trillion tera T Distance to planet Jupiter
109 1,000,000,000 one billion giga G The diameter of the Moon's orbit
106 1,000,000 one million mega M Half-way across the USA
103 1,000 one thousand kilo k A kilometre: a 15 minute walk
102 100 one hundred hecto h The height of a giant sequoia tree and the Statue of Liberty
101 10 ten deca The height of a house
100 1 one The length of an adult arm
10-1 0.1 one tenth deci d The length of your hand
10-2 0.01 one hundredth centi c The width of a finger
10-3 0.001 one thousandth milli m The width of a pin
10-6 0.000 001 one millionth micro u The size of a living cell
10-9 0.000 000 001 one billionth nano n The size of a water molecule
10-12 0.000 000 000 001 one trillionth pico p Only atoms are at this scale
10-15 0.000 000 000 000 001 one quadrillionth femto f The size of a proton
10-18 0.000 000 000 000 000 001 one quintillionth atto a ? We know of nothing this small!


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