Reference library128 entries

Author: Tommy C. Moran

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

Oct 2026

How to Round to Significant Figures in MATLAB: Precision Control for Engineers

MATLAB has no single sig-fig rounding function, but you can combine round, floor, log10, and sprintf/fprintf to control significant digits accurately.

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Oct 2026

Standard Deviation Reporting

Why Does My Teacher Round the Mean Differently Than the Standard Deviation?

The mean and standard deviation are rounded differently because they answer different questions: the mean follows decimal-place precision of the data, while the SD…

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Oct 2026

Significant Figures

Significant Figures in Calibration Certificates: How to Report Uncertainty per GUM

In calibration certificates, report expanded uncertainty U to at most two significant figures per GUM 7.2.6, then round the measured value to the same…

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Oct 2026

GUM Guide

Why Leading Zeros Are Not Significant in the GUM: A Metrology Perspective

An authoritative explanation of why leading zeros serve only as placeholders and do not contribute to the precision of a measurement according to GUM…

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Oct 2026

MATLAB

Significant Figures in MATLAB: Rounding, Display, and Precision Control

A comprehensive guide to managing numerical precision in MATLAB, distinguishing between internal double-precision storage and formatted output for significant figures.

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Oct 2026

Excel

How to Round to Significant Figures in Excel and Google Sheets

Learn the authoritative methods for implementing significant figure rounding in spreadsheet software using mathematical formulas and precision standards.

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Oct 2026

Python

Sig Figs in Python: round(), format(), and Decimal — Which One Follows ASTM E29?

Python's round() and format() use half-even ties, matching ASTM E29 for exact ties, but binary floats can break decimal rounding. Decimal.quantize() is the reliable…

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Oct 2026

Measurement Uncertainty

Type A vs Type B Uncertainty: What’s the Difference and When to Use Each

Type A uncertainty is evaluated by statistical analysis of repeated observations; Type B uncertainty is evaluated by any other documented method, such as calibration…

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Oct 2026

Python

How to Round to Significant Figures in Python Using the decimal Module

Use Decimal.quantize with an exponent derived from the adjusted exponent to round to n significant figures, choosing ROUND_HALF_EVEN for standards-aligned ties.

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Oct 2026

Rounding Rules

When to Round in Multi-Step Calculations: A Decision Tree for Students and Professionals

To prevent rounding error accumulation, maintain maximum precision throughout intermediate steps and round only at the final result based on the limiting significant figure.

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