Off topic, but neat speedometer trick. Preconditions: * You have an analog speedometer which is in both miles and km/h. [1] * You are on a road trip on a hig

Off topic, but neat speedometer trick. Preconditions: * You have an analog speedometer which is in both miles and km/h. [1] * You are on a road trip on a highway, driving at or near 100km/h. In Canada on the 400 class highways, both are often true.[2] The trick is simple. It must be, I figured it our when I was a kid looking of my father's shoulder while he drove. Notice how 100km/h nearly aligns with 60 mph on the speedometer? You can use the mph gauge as the approximate number of minutes required to travel a given distance in km. Say you just saw a sign saying a rest stop was in 42 km. To estimate the time to your rest stop, just line up 42 km/h with the corresponding number on the mph scale, which in this case gives about 27 min. [1] http://www.storiesfromschoolaz.org/wp-content/uploads/2013/03/read-for-speed-0-to-120.jpg http://www.storiesfromschoolaz.org/wp-content/uploads/2013/0... [2] I drive at 110 because the trucks drive at the same speed, so you don't have to pass as often.