Reference library69 entries

Author: Tommy C. Moran

Practical explanations, worked examples, and reference notes for reporting numbers correctly.

Truncation vs Rounding: When Cutting Digits Is Correct

Truncation and rounding are distinct digit-reduction methods. Truncation simply cuts off excess digits, while rounding adjusts the retained digits based on the discarded portion.…

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Orders of Magnitude Explained

{ “title”: “Orders of Magnitude Explained: Precision, Rounding, and Significant Figures”, “slug”: “orders-of-magnitude-explained”, “excerpt”: “A comprehensive guide to understanding orders of magnitude, their role…

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Exact Numbers Have Infinite Significant Figures — Here’s What That Means

Exact numbers, such as counted quantities and defined conversion factors, possess an infinite number of significant figures. This article explains the rule, provides worked…

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Error Propagation

Propagating Uncertainty Through Addition and Multiplication: Rules, Examples, and Standards

Learn how to propagate uncertainty when adding, subtracting, multiplying, and dividing measured values. Understand the significant figure rules, the GUM approach, and common pitfalls.

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What Is ASTM E29 Rounding and Who Uses It?

ASTM E29 defines the standard practice for rounding test data to determine conformance with specifications. It is widely used in materials testing, manufacturing, and…

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Significant Figures

Significant Figures in Multi-Step Calculations: When to Round

Learn the correct rounding strategy for multi-step calculations to preserve precision and avoid error propagation.

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Significant Figures

Why 1200 Can Have 2, 3, or 4 Significant Figures

The number 1200 is ambiguous because trailing zeros without a decimal point are not significant. Depending on context, it can have 2, 3, or…

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Double Rounding Error

The Double Rounding Error That Changes Your Final Answer

Double rounding—rounding an intermediate value and then rounding again—can produce a different final result than a single direct rounding. Learn the rules, standards, and…

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How to Round to Significant Figures in Excel (ROUND + LOG10 Method)

Learn the exact Excel formula to round any number to a specified number of significant figures using ROUND and LOG10, with worked examples, standards…

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pH and Sig Figs: Why Only the Decimals Count

In pH measurements, only the digits after the decimal point are significant. This article explains the logarithmic basis, the rules, and common pitfalls.

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