Featured contributor MSc Applied Statistics; 7 years in analytics and data tooling.

Daniel Oh

Senior Contributor, Math & Statistics

0 calculators 0 articles Member since Jun 2026

About

Daniel writes and reviews the math and statistics calculators. His explainers lean on worked examples, clean formulas, and obvious edge cases so readers can copy the logic straight into a spreadsheet.

He previously worked as a data scientist at a consumer-tech startup before moving into full-time writing and tooling.

Areas of expertise

Statistics Probability Percentages Data analysis

Education & credentials

BSc Mathematics — University of Toronto
MSc Applied Statistics — ETH Zürich

Physics

Telescope Angular Magnification and Resolving Power Calculator

Calculates telescope angular magnification and minimum resolvable angle using the Rayleigh criterion. Larger aperture an...

basic

19,159 4.1 1 min

Math / Geometry

Circular Segment Area Calculator

Compute the area of a circular segment (the region between a chord and an arc) from the circle radius and the central an...

basic

14,981 4.9 1 min

Chemistry / Reactions

Equilibrium Constant Calculator

Compute the equilibrium constant K_c from the concentrations of two products (with stoichiometric coefficients 1) divide...

basic

5,059 4.0 1 min

Math / Percentage

Scientific Notation Converter

Convert numbers between standard decimal form and normalized scientific notation (a × 10ⁿ with 1 ≤ |a| < 10).

basic

5,330 4.1 1 min

Math

Sample Excess Kurtosis from 4th Moment and Variance Calculator

Compute the excess kurtosis of a distribution from its centred fourth moment m₄ = E[(X − μ)⁴] and the variance σ²: exces...

basic

23,412 4.4 1 min

Math / Geometry

Vector Magnitude Calculator

Compute the magnitude (length) of a 3D vector and its unit vector from the three components.

basic

14,417 4.1 1 min

Statistics / Probability

Dice Expected Value Calculator

Compute the expected value and variance of rolling N identical fair dice (each with S sides), using E = N · (S+1)/2 and...

basic

7,023 4.0 1 min

Math

Arithmetic Series Sum from First Term, Last Term, and Count Calculator

Compute the sum of an arithmetic series: S_n = n(a₁ + aₙ)/2, where a₁ is the first term, aₙ the last, and n the count of...

basic

7,923 4.4 1 min

Math / Geometry

Rectangle Area & Perimeter Calculator

Compute the area, perimeter, and diagonal of a rectangle from its length and width.

basic

3,155 4.0 1 min

Math / Geometry

Midpoint Calculator

Find the coordinates of the midpoint of the segment connecting two points in the plane.

basic

9,509 3.8 1 min

Statistics

Margin of Error from Sample Size Calculator

Compute the margin of error E for the mean from the sample standard deviation, sample size, and chosen confidence level...

basic

9,714 4.4 1 min

Math / Percentage

Number of Divisors from Prime Factorisation Calculator

Calculates the number of positive divisors of n = p₁^e₁ × p₂^e₂ × … as d(n) = (e₁+1)(e₂+1)…. For small n, also computes...

basic

14,074 4.1 1 min

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tutorial Math

Percentages Without the Headache

Every "X% of Y" problem, every "what percent of", every percent-change question — written out the way you'd actually say them.

Daniel Oh

Jan 16, 2026 3 min

explainer Statistics

Standard Deviation in Five Minutes

Standard deviation is "average distance from the average". That one sentence covers 90% of everything you ever need to remember about it.

Daniel Oh

Dec 6, 2025 3 min

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Browse categories

Daniel Oh

Telescope Angular Magnification and Resolving Power Calculator

Circular Segment Area Calculator

Equilibrium Constant Calculator

Scientific Notation Converter

Sample Excess Kurtosis from 4th Moment and Variance Calculator

Vector Magnitude Calculator

Dice Expected Value Calculator

Arithmetic Series Sum from First Term, Last Term, and Count Calculator

Rectangle Area & Perimeter Calculator

Midpoint Calculator

Margin of Error from Sample Size Calculator

Number of Divisors from Prime Factorisation Calculator

Percentages Without the Headache

Standard Deviation in Five Minutes