A centimetre (American spelling: centimeter, symbol cm) is a unit of length in the metric system, equal to one hundredth of a metre, which is the current SI base unit of length. Centi is the SI prefix for a factor of 10 − 2.] Hence a centimetre can be written as 10×10 − 3 m (engineering notation) or 1 E-2 m (scientific E notation) — meaning 10 × 1 mm or 1 m / 100 respectively. The centimetre is the base unit of length in the now deprecated centimetre-gram-second system of units.
Though for many physical quantities, SI prefixes for factors of 103 - like milli and kilo - are often preferred by technicians, the centimetre remains a practical unit of length for many everyday measurements. A centimetre is approximately the width of the fingernail of an adult person.
What is a Yard?
(from Wikipedia)
A yard (abbreviation: yd) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. Its size can vary from system to system. The most commonly used yard today is the international yard which by definition is equal to 0.9144 metre.
The yard is used as the standard unit of field length measurement in both the American and Canadian games of football (although Canada has officially adopted the metric system).
The yard is used on road signs and markers in the UK. Indeed, it is illegal to display length/speed in metres/kilometres on road signs in the UK, as this would cause confusion.
A corresponding unit of area is the square yard.
Yard is also a slang word, used particularly in currency trading, for one billion units of a currency, e.g., a yard of dollars is $1bn, thus a buyer of a billion dollars could say "I'm a buyer of a yard of dollars."
