A power of ten is \(10^k\) for some non-negative integer \(k\): 1, 10, 100, 1000, 10000, 100000, 1 000 000…
The decimal place-value system is built from powers of ten: each position represents \(10^k\). The metric (SI) prefix system is also built from powers of ten — kilo (\(10^3\)), mega (\(10^6\)), giga (\(10^9\)), tera (\(10^{12}\)), and so on.
In scientific notation, all numbers are written as \(a \times 10^k\) for some \(1 \leq |a| < 10\), making powers of ten the canonical scale unit for human-readable orders of magnitude.