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

Capacitor Energy Stored Calculator

Calculates energy stored in a capacitor from capacitance and voltage, along with charge stored Q = CV.

basic

11,627 3.9 1 min

Other

Months Between Dates Calculator

Compute the number of whole months, fractional months (using 30.4375 days/month), total weeks, total days, and a friendl...

basic

6,465 4.0 1 min

Math / Geometry

Ellipsoid Volume from Three Semi-Axes Calculator

Compute the volume of an ellipsoid (a 3-D generalization of an ellipse) from its three semi-axis lengths a, b, c: V = (4...

basic

1,446 4.3 1 min

Math / Geometry

Cube Surface Area Calculator

Calculate the surface area, volume, and space diagonal of a cube from a single side length.

basic

17,939 3.8 1 min

Math

Confidence Interval for a Mean (t-Distribution) Calculator

Compute the confidence interval for a population mean using the t-distribution (sample standard deviation, df = n − 1):...

basic

23,257 4.2 1 min

Math / Percentage

Test Time Per Question Calculator

Compute the average minutes you can spend per question on a timed test from the total test length, the number of questio...

basic

10,875 4.1 1 min

Math / Fractions

LCM Calculator

Find the least common multiple of two or more whole numbers, with the full prime-factor breakdown.

basic

17,193 4.5 1 min

Math

Cosine Similarity from Dot Product and Norms Calculator

Compute the cosine similarity between two vectors when only the dot product and the two L2-norms are pre-computed: cos θ...

basic

2,405 5.0 1 min

Math

Negative Binomial Distribution PMF Calculator

Compute the negative binomial PMF — the probability that the r-th success occurs on the k-th trial, given a per-trial su...

basic

2,276 4.4 1 min

Statistics / Probability

Permutation & Combination Calculator

Count how many ways to choose or arrange r items from a set of n — both nPr and nCr, with a short breakdown of why they...

basic

19,329 4.9 1 min

Math / Geometry

Regular Polygon Interior Angle Calculator

Compute the interior angle of a regular n-gon and the sum of all interior angles: each = (n − 2) · 180 / n; sum = (n − 2...

basic

11,158 4.7 1 min

Math / Geometry

Regular Polygon Exterior Angle Calculator

Compute the exterior angle of a regular n-gon (sum is always 360°): each = 360 / n. Reports the corresponding interior a...

basic

14,518 4.9 1 min

Showing 349 to 360 of 545 results

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

Calcify

Browse categories

Daniel Oh

Capacitor Energy Stored Calculator

Months Between Dates Calculator

Ellipsoid Volume from Three Semi-Axes Calculator

Cube Surface Area Calculator

Confidence Interval for a Mean (t-Distribution) Calculator

Test Time Per Question Calculator

LCM Calculator

Cosine Similarity from Dot Product and Norms Calculator

Negative Binomial Distribution PMF Calculator

Permutation & Combination Calculator

Regular Polygon Interior Angle Calculator

Regular Polygon Exterior Angle Calculator

Percentages Without the Headache

Standard Deviation in Five Minutes