Science

Science questions are where orders of magnitude matter more than digits. Distances, counts and temperatures at astronomical or microscopic scale are impossible to recall and entirely possible to derive, usually from one known quantity and one ratio. Aim at the exponent and the rest follows.

The most transferable anchors are the size of the Earth, the distance to the Sun, and the speed of light. Between them you can reconstruct most of the astronomy in this category — planetary distances are quoted as multiples of one, light travel times follow from another, and orbital speeds fall out of the geometry.

For biology, the reliable route is volume divided by unit size: how many cells, neurons, bacteria or atoms fit in a given space. And several figures here are estimates rather than counts, with genuine uncertainty that the sources state openly. Where a number is a scientific reconstruction rather than a measurement, the page says so.