04 Try it yourself Interactive
Two runs share one console. The sieve is the same 2-to-30 grid from section 02: each press either picks the next prime, skips a p that is already crossed out, or strikes one multiple, and the line of code responsible lights up beside it. Watch for the crosses that land on a number twice — that is the redundancy the p² start is fighting. Switch to Euclid and the same Next button reduces 30 and 18 one division at a time until the remainder hits zero.