Scientific notation and significant figures

Last updated: 2026-06-09. Clarified IB expectations of sf in answers

For numbers less than $1$, the number of zeros appear in the exponent as a negative number.

For numbers greater than $1$, the number of digits between the first digit and the decimal point appear in the exponent as a positive number.

Do not use computer notations such as $7.45\text{E}-3$ or $1.8\text{E}5$ on assessments.

The number of significant figures a number has is the number of digits in the scientific notation. This means $2.07 \times 10^5$ and $207000$ both have three significant figures, but $2.070 \times 10^5$ has four. Other numbers with 3 sf include: $12.0$, $0.0543$, $0.100$, $0.101$.

If the answer can only be an integer, such as the quantity of some items, $n$ in SL binomial distribution, or the number of compounding periods in compound interest, report the answer in full.

Use more sf than what you write on the exam paper. Use the unrounded intermediate values from your calculator storage, without needing to copy all the digits onto the paper. IB also recommends doing the same for final answers in subsequent calculations. See storage on TI-84 Plus CE for tips and methods on how to store and reuse values. Report final answers exactly (eg $\sqrt 2$), or to 3 sf, or as otherwise specified in the question (eg in finance questions). The answer does not need to be in scientific notation.

A penalty is given each time the approximate final answer does not have 3 correct sf. At its discretion, IB may penalize giving too many significant figures in final answers, especially when question uses measured and rounded values such as distance, mass, bearing, etc. In any case, only three-figure bearings (eg $045\degree$) are accepted.

In “show that” proofs, where an approximate value is given, you must write down one additional correct sf. For instance, if asked to show that $x = 0.1234$, you should provide a final answer of $x = 0.12338$. This has been policy since 2024.