This is the boss. No calculator — and $\pi$, the number that never ends, stays a SYMBOL: every line's answer is a clean number times π, so carry the coefficient and let π ride. Only the very last line turns π into a number, and today it rounds all the way to 3 — the exam-hall estimate, close enough to size a paint order. One silo: a cylinder wearing a half-sphere dome. Fill it, then paint it — and every answer feeds the next, so write each line down. One early slip pours all the way down the silo.

Everything from the chapter rides along: the cylinder, the hemisphere, the wall, the dome's curve. 5★ under par here is the chapter crown. Ladder up.