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

Math / Percentage

Mean Absolute Deviation Calculator

Compute the mean absolute deviation (MAD) — the average absolute distance of each value from the mean — alongside the me...

basic

24,680 4.3 1 min

Physics / Mechanics

Escape Velocity from Planet Surface Calculator

Calculates escape velocity v_esc = √(2GM/R) and the corresponding kinetic energy needed per kg of payload. For Earth: M...

basic

13,939 4.8 1 min

Math

Harmonic Series Partial Sum H_n Calculator

Compute the n-th partial sum of the harmonic series Hₙ = Σₖ₌₁ⁿ 1/k. Also reports the Euler-Mascheroni approximation Hₙ ≈...

basic

11,101 4.8 1 min

Math

Shannon Entropy of a 3-Outcome Discrete Distribution Calculator

Compute the Shannon entropy H of a 3-outcome discrete distribution: H = −Σ pᵢ · log₂ pᵢ, in bits. Entropy is the average...

basic

7,388 4.3 1 min

Math / Percentage

Exponential Growth Calculator

Project a quantity that grows continuously at a constant rate r over time t, using the standard exponential growth model...

basic

19,668 4.3 1 min

Statistics / Descriptive

Mean, Median, Mode Calculator

Paste a list of numbers to get mean, median, mode, range, and standard deviation instantly.

basic

25,073 4.2 1 min

Physics

LED Series Resistor from Supply and Forward Voltage Calculator

Calculates the required series resistor: R = (V_supply − V_f) / I_f, where V_f is LED forward voltage (~2.0–3.5 V) and I...

basic

11,480 4.0 1 min

Physics / Electricity

Parallel Capacitance Calculator

Compute the equivalent capacitance of two capacitors connected in parallel and in series.

basic

10,197 4.5 1 min

Math / Geometry

Pythagorean Theorem Calculator

Find the hypotenuse from two legs, or recover a missing leg from the hypotenuse and the other leg, using the Pythagorean...

Featured basic

17,876 4.6 1 min

Statistics

Combined Mean of Two Groups Calculator

Compute the combined (weighted) mean of two groups given each group's mean and sample size: x̄ = (n₁·x̄₁ + n₂·x̄₂) / (n₁...

basic

17,942 4.2 1 min

Chemistry / Solutions

pOH Calculator

Compute pOH from hydroxide ion concentration and the matching pH at 25 °C.

basic

14,544 3.8 1 min

Statistics / Descriptive

Margin of Error Calculator

Estimate the margin of error of a survey result from sample size, observed proportion, and confidence level.

basic

4,128 5.0 1 min

Showing 289 to 300 of 566 results

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

Mar 20, 2026 3 min

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 7, 2026 3 min

Reviewed by Daniel Oh

These calculators were technically reviewed by Daniel Oh for accuracy.

Health

Young's Rule Pediatric Dose Calculator

Calculate an age-based pediatric dose from a known adult dose using Young’s Rule. A quick educational tool for students...

basic

22,632 5.0 1 min

Best Free Calculator

Browse categories

Daniel Oh

Mean Absolute Deviation Calculator

Escape Velocity from Planet Surface Calculator

Harmonic Series Partial Sum H_n Calculator

Shannon Entropy of a 3-Outcome Discrete Distribution Calculator

Exponential Growth Calculator

Mean, Median, Mode Calculator

LED Series Resistor from Supply and Forward Voltage Calculator

Parallel Capacitance Calculator

Pythagorean Theorem Calculator

Combined Mean of Two Groups Calculator

pOH Calculator

Margin of Error Calculator

Standard Deviation in Five Minutes

Percentages Without the Headache

Reviewed by Daniel Oh

Young's Rule Pediatric Dose Calculator