**
Conversion Factor
** -
A clever way of writing 1 as a fraction in which
the numerator is equal to the denominator but the
numerator and the denominator have different
units. For example, (1,000 m)/(1 km) is a conversion factor because 1,000 m = 1
km. (1 ft)/(12 in) is a conversion factor because 1 ft = 12 in.

**
Precise
** -
A term used to connote how accurate a measurement is. The more significant
digits in a measurement, the more precise that measurement is.

**
Scientific Notation
** -
A number written as a product of a single digit and a power of 10.

**
Significant Digits
** -
The number of digits after the given number has been put into scientific
notation. The number of digits that are known in a measurement, plus one digit
that is estimated.