Coding classes in Rutland

The learner downloads two things: the 2021 Census count for each of Rutland's 128 output areas from Nomis, and the ONS lookup that says which parish each output area belongs to. Every output area appears exactly once, so the pieces fit into a tree with 168 nodes: one root for the county, 39 parish branches and 128 leaves. Output areas range from 103 residents to 1,221, averaging about 321. Now the program walks the tree in different orders, each useful for a different job.

The post-order walk adds the leaves up to parishes and the parishes up to the root, and the root comes to 41,048. The published county figure is 41,049. The program is right and so is the census; the gap comes from how the ONS protects privacy. Its own methodology says it added "noise" to every Census 2021 dataset, that a typical dataset has around 14 per cent of its counts changed by a small amount, and that "the randomness may mean small changes to totals". A county and its 128 areas are separate published counts, each with its own tiny adjustment, so their sums need not match exactly.

That is the lesson most worth keeping. When the sum of the parts and the published total disagree slightly, the right move is not to force them to agree, and not to add up the parts and call it the official figure. You report the published total as published, label your own sum as yours, and explain the difference. Every figure on this page follows that rule.

So a young person in Rutland should learn to code in 2026 to understand where numbers come from, not only how to add them. The longer argument is in why teenagers should still learn to code in 2026.