Loosely speaking, the power of 10 that can be used to represent a number—so n is the order of magnitude of k × 10n. Different conventions restrict k to the ranges 1/√10 ≤ k < √10 or 0.5 < k ≤ 5 or 1 ≤ k < 10, the last being scientific notation.
Chemical Engineering
A designation used to describe a difference between two numbers with one being ten times greater than that of the other.