Maths
Percentages, fractions, equations and averages.
Arithmetic that is easy to do and easy to get wrong. Percentages are the clearest case: a rise of 25% followed by a fall of 25% does not put you back where you started, and the percentage change calculator states which base it worked from, so the answer can be checked rather than trusted.
Arithmetic, shapes, or statistics
The everyday end is percentages, ratios, fractions and averages — small sums that turn up in a shop, a recipe or a spreadsheet. The geometry set covers area, volume, triangles, slope, angles and the golden ratio, and each states the formula it used, because a triangle solved from two sides and the angle between them is a genuinely different calculation from one solved from three sides.
The statistics set — standard deviation, z-score, p-value, confidence interval, sample size, probability and combinations — is where the sample-versus-population distinction bites, so each tool says which one it assumed. The scientific calculator parses a whole typed expression instead of making you press keys in order, which means you can read back what you meant and fix it. Aspect ratio is here because it is a ratio, not because it is about pictures. Interest and margin are Finance; material quantities are Home & workshop.