Jul 2026
Orders of Magnitude
Orders of Magnitude Explained
In science and engineering, understanding the scale of a quantity is as important as its exact value. The concept of an order of magnitude…
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Reference library128 entries
Author: Tommy C. Moran
Practical explanations, worked examples, and reference notes for reporting numbers correctly.
Jul 2026
Exact Numbers
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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Jul 2026
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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Jul 2026
ASTM E29
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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Jul 2026
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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Jul 2026
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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Jul 2026
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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Jul 2026
Rounding vs Significant Figures
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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Jul 2026
Chemistry
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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Jul 2026
Ambiguous Trailing Zeros
The Overline (Bar) Notation for Ambiguous Trailing Zeros
Learn how the overline (bar) notation resolves ambiguity in trailing zeros, with rules, examples, standards citations, and common pitfalls.
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