When I am in Europe, it is handy that I am a railfan, because I can remember that the fastest British trains (except Eurostar) go at 125 mph which is 200 kM/hr in round figures and the French TGV goes at 300 kM/hr which is 186 mph. Also a kM is 5/8 of a mile. Thus 50 miles is 80 km etc. These generally get me through. Plus a little rhyme which the British Government used in publicity material at the time metrication started nearly 50 years ago - I can't remember it exactly but it goes something like this: "It's simple, you see - a metre is three foot three".
But the thing is, if you live with a measurement system, you get used to what it feels like. You know what it will feel like if the temperature is going to be 20 degrees, or how long it would take you to walk somewhere 1 kilometre away, or what a pack of rice weighing 1 Kg, or 2 litres of milk, will feel like when you pick them up, and how long they will last.
Being involved with marijuana in my youth taught me that 1 ounce = 28.35 grammes, and 1 Kg = 2.2 pounds.
In Canadia (home of the Canadians), they sell sugar in two kilo bags. That's four-point-four pounds. In the States, they sell sugar in five pound bags. The Canadians are gettin' screwed.
