In much of UK and international school math, standard form means writing a number as a × 10ⁿ with 1 ≤ |a| < 10 and n an integer. That is the same structure many curricula call scientific notation — same powers of ten, sometimes different classroom vocabulary.
This guide shows how to convert large and small decimals into standard form, how engineering notation groups exponents by threes, how significant figures ride along with a, and how to convert back. Practice with the free standard form converter — decimal ↔ a×10ⁿ, engineering form, sig figs, and order of magnitude client-side.
For a dedicated scientific-notation walkthrough, see the scientific notation guide; powers of ten themselves are covered in the power calculator guide.