South Africa was a British colony until 1961, so the imperial system of measurement was standard. When the country achieved independence, the metric system was adopted. We also changed from the South African pound to South African rands.
This meant that for a long time after I started school, we used to convert from one to the other – both currency and measurements. Partly because some text books were pre-1961, partly because shops often displayed both, partly because my parents always did it.
After the internet revolutionised the world, this skill has proved invaluable to me. I can figure out recipes, online product specifications, weight conversions, sizes etc pretty quickly without using a converter.