Whether it’s because of the mental arithmetic my Dad used to make us work our way through as a child, my own obsessive compulsive inclinations or because of Donald in Mathemagic Land, I tend to set myself little arithmetic challenges all over the place. It’s a useful thing; every now and then it applies to a business or investment decision.

On the commute, though, it’s a way of killing dead time. On the drive in, I work out my average speed including traffic lights (35 mph). I estimate the potential total mileage the car can cope with on the commuter run (about 150 miles), and what that means for fuel consumption (75 days of there-and-back to Basingstoke station, or about three working months between refuels if I don’t use the car for anything else), and what that costs (currently about £52 or £17ish a month).

On the train, I try to work out its average speed (just under 80 mp/h for the longest leg of the journey), although mostly these days I read and worry that I’m going to get to the end of the novels I’m reading too quickly and end up in search of another fictional universe to devour on the trip. Of course, many days the iPad comes out and its time to get through email and work, but the last couple of weeks the train has been too crowded for much of that…

How do you deal with your commute, long or short? It’s certainly a far cry from the days in London when I tried to beat the record for my 16 minute bike ride across the park…