Learn German: Wir mischen fünf Milliliter Extrakt. - We are mixing five milliliters of extract.

In German, masculine and neuter nouns used as units of measurement (like Milliliter, Liter, or Kilo) do not take a plural ending after a number. Even though it is plural in meaning, the form stays exactly the same as the singular: fünf Milliliter.

Would a feminine unit of measurement work the same way as Milliliter?

No. The zero-plural rule is only for masculine and neuter units of measurement. If you were mixing cups of extract, you would have to pluralize the feminine noun Tasse, making it fünf Tassen Extrakt.

Why is there no German word for "of" before Extrakt?

When expressing measurements or quantities, German does not use a translation for "of" like English does. You just place the measured substance directly after the unit of measurement. So, "five milliliters of extract" translates directly to fünf Milliliter Extrakt.

What case are Milliliter and Extrakt in this sentence?

They are in the accusative case because the entire quantity phrase is the direct object of the verb mischen. When a substance follows a unit of measurement, it usually takes the same case as that unit. However, because there are no articles or adjectives here, neither noun visibly changes its form.