Scientific notation writes a number as a × 10^n where the coefficient satisfies 1 ≤ |a| < 10 (zero is the special case 0 × 10^0). That single-digit rule is the whole point of the form: one look tells you the order of magnitude.
This page's framing is a normalize gate, with a decimal-shift peel, a decade / SI ladder, and a sig-fig honesty rail. Engineering notation appears as a ladder rung (exponent multiple of 3), not as a competing solve twin. It is not the rule-of-three board, not ratio equivalent-forms, not interest year-path / EAR, and not a base-converter or expression evaluator.
Decision framing: “What is the normalized a × 10^n, how far did the point move, and which SI decade am I in?”
Educational notation literacy only. Not a computer-algebra system or exam oracle. Confirm rounding and significant-figure rules with your course when grades are on the line. See our disclaimers.