Daniel Oh
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
Math / Percentage

Covariance Calculator

Compute the sample covariance, population covariance, Pearson correlation r, and the slope of the regression line from t...

basic
8,461 4.5 1 min
Math / Geometry

2D Rotation Matrix Calculator

Compute the entries of a 2-dimensional rotation matrix R(θ) = [[cos θ, −sin θ], [sin θ, cos θ]] and the result of rotati...

basic
22,121 4.2 1 min
Math / Percentage

Prime Number Checker

Check whether any positive integer up to a trillion is prime, and if not, the smallest factor that proves it composite.

basic
6,496 4.6 1 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 Daniel Oh
3 min