- I bought two dozen of mangoes.
- I bought two dozens of mangoes.
- My office buys five kilogram of paper every month.
- My office buys five kilograms of paper every month.
In 1& 2 I think 1 is correct. And hence in 3&4 I think 3 should be the correct one.
It is my exam question and in provisional answer key suggest 1 and 4 is correct. Please explain why it is so.