This is the boss. No calculator. Every figure has been chosen so the whole card runs in your head: the pace counts multiply cleanly, the ruler reading lands on a round number of metres, the climbing section is a Pythagorean triple, and Naismith comes out in whole minutes.

Six lines, and every answer feeds the next: paces to metres, ruler to metres, the two legs to a total, the contour crossing to a ground distance, the total plus the climb to a time, and the outbound bearing to the bearing home. Write each line down as you go — one slip at the top rolls all the way to the road head.

Three things to hold as you work. Twelve minutes per kilometre, plus six minutes per 60 m of climb. On a 1:50,000 sheet one centimetre is half a kilometre. And Naismith is charged on the map distance, not the ground distance — the slope's stretch is a couple of percent and the rule already prices the hill, in the currency that actually costs you: time.

The last line is the one people fumble when they are tired and it is getting dark, which is exactly when it is needed. Add 180. If you sail past 360, take 360 back off. 5★ under par here is the chapter crown. Clock in.