Reference library35 entries

Category: Significant Figures

Authoritative reference for significant figure rules, precision, and rounding, including a top-rated sig fig calculator.

Oct 2026

Significant Figures

Why Did My IB Teacher Mark My Sig Figs Wrong? Common IA Deductions Explained

IB science IA marks often penalize significant figures because reports must show precision consistent with measurements and uncertainty. This guide explains the common deductions…

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Oct 2026

Overline Notation

When to Use Overline Notation vs Uncertainty (±) in Lab Reports

Overline notation marks significant trailing zeros or repeating decimals; ± states measurement uncertainty. In lab reports, use ± whenever uncertainty is known, and reserve…

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Oct 2026

Significant Figures

Why Did My Teacher Mark This Wrong? The 7 Most Common Sig Fig Mistakes in Chemistry

A chemistry teacher marks significant-figure answers wrong when the reported digits overstate or understate measurement precision. Here are the 7 most common sig fig…

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Oct 2026

Significant Figures

Why Does My Calculator Give a Different Sig Fig Answer Than My Teacher?

Calculators do not track significant figures; they compute at full precision. Your teacher applies measurement-based sig fig rules and a rounding convention, which can…

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Oct 2026

Exact Numbers

Why Is a Mole Exact? The Difference Between a Count and a Measurement in Chemistry

The mole is exact because the SI defines it by an exact fixed value of the Avogadro constant; however, most laboratory amounts are obtained…

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Oct 2026

Significant Figures

Significant Figures in Engineering Drawings: How to Read and Apply Tolerance Rounding

Engineering drawings use significant figures and decimal places to encode precision and tolerance. Learn the standards, rounding rules, worked examples, and pitfalls for reading…

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Oct 2026

Significant Figures

How to Round a Number in Scientific Notation to a Given Number of Significant Figures

Round the coefficient to the required number of significant figures, apply the correct tie convention, and renormalize if the coefficient reaches 10.

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Sep 2026

Ambiguous Trailing Zeros

How to Avoid Ambiguous Trailing Zeros in Spreadsheets and Databases

Learn how to maintain metrological integrity in digital data by preventing the loss or artificial addition of trailing zeros in spreadsheets and databases.

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Aug 2026

Significant Figures

Which Zeros Are Significant? Every Case, Settled.

Zeros are significant when they are between non-zero digits, after a decimal point when trailing, or in the coefficient of scientific notation. Leading zeros…

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Aug 2026

Significant Figures

Significant Figures: The Complete Guide to Rules & Zeros

Every significant figures rule explained with worked examples — zeros, arithmetic, exceptions, and why AP, IB, and ASTM E29 don't always agree.

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