Hi, what is the rule with regard to units of measurement in abbreviation and the use of plurals. To illustrate what I mean, the plural form is needed when the unit is expressed in full: 1. I drink 250 milliliters of milk. If abbreviation is used, there is no plural form: 2. I drink 250 ml of milk. But, in speech I often hear people express the abbreviated unit in plural form: 3. "I drink 250 mls of milk." Is sentence 3 wrong, or is it customary to use the plural form in speech?