Scientific notation and significant figures

Last updated: 2026-04-07.

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 $2.07 \times 10^5$ has three significant figures, but $2.070 \times 10^5$ has four.

When using a calculator, store all intermediate values on the calculator, with ans or a letter storage, then round the final answer correct to three correct significant figures. The answer does not need to be in scientific notation. See storage on TI-84 Plus CE for tips and methods on how to do so.

At its discretion, IB may penalize giving too many significant figures in final answers. When question uses measured and rounded values such as distance, mass, bearing, etc., the final answers should have exact three significant figures. It’s just good habit to always give approximate answers to exactly three significant figures.

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

If the answer can only be an integer, such as the quantity of some items, $n$ in SL binomial distribution, the number of compounding periods in compound interest; or an exact number (like $\frac\pi3$), then report the answer in full.