ONE RULE A DAY: MONEY, MEASUREMENT, PERIOD AND DISTANCE

English for Today by Ganiu Abisoye Bamgbose (Dr GAB)

ONE RULE A DAY: MONEY, MEASUREMENT, PERIOD AND DISTANCE

200 dollars ~are~ enough to fix everything (nonstandard).
200 dollars is enough to fix everything (standard).

10 kilometres ~seem~ a far journey (nonstandard).
10 kilometres seems a far journey (standard).

60 years ~are~ the minimum age of retirement (nonstandard).
60 years is the minimum age of retirement (standard)

When distance, money, period and measurement are used at the subject position of a sentence, the verb should be singular.
GAB