Number that characterizes an approximate value of a measure or of a more precise number.

The order of magnitude of a number can be the power of 10 closest to the number or a specific place value chosen to represent it.

### Examples

- The order of magnitude of the height of a person is the foot, since height is measured in feet.
- The order of magnitude of the age of the Earth is billions of years, since available scientific data estimates the age of the Earth at 4.568 billion years.
- The order of magnitude of the age of the universe is billions of years, since available scientific data estimates the age of the universe at 13.798 billion years.
- The order of magnitude of the diameter of a hydrogen atom is the picometre (\({10}^{-12}\) metres)
- If we round the value of π, 3.141 592 654 …, to the nearest hundredth, we obtain π ≈ 3.14.