A measurement is a quantitative observation.
Measurements consist of both a number and a unit.
2.1 Scientific Notation. When we deal with very large numbers or very small numbers, it is better to express them in scientific notation. We have arrived to this answer by placing a decimal point after the first digit and counting the number of figures to the right of the decimal point until the end of the number. The number of places becomes the exponent. Likewise we represent a very small number, say one second in units of hours as 0.0002778 hr or 2.778 X 10-4.