The use of the implicit referent is commonplace throughout our culture. Prices are usually given in the form of three ninety-nine or two twenty-five. We talk about the size of a motorcycle as a seven fifty or a twelve hundred and snowboarders and skateboarders routinely do one-eighties and three sixties. The time is always given without a referent and sportscasters could not survive if they had to give the referent for every number they used. An ERA of point three five eight, hitting three forty, winning five to three and declaring at five hundred twenty six for six.
This is all well and fine when you are a native to the culture but when you are not it can cause considerable difficulties. For example, in the above examples what does "declaring for five hundred twenty six for six" mean? And if you had to fill your car with gas in Montreal about how many litres would it take?
When we teach math to English Learners we must remember to a) make the referents explicit and b) give students a sense of the size of each referent so they can understand the significance of the measurements they are using.