1. Two hundred and fifty-six grains of rice amounts to one spoon of rice.

Question

2. Two hundred and fifty-six grains of rice amounts to one spoonful of rice.

3. Two hundred and fifty-six grains of rice amounts to a spoonful of rice.

4. Two hundred and fifty-six grains of rice amounts to a spoon of rice.

(Are the sentences all grammaticl and the same?)

Answer 1

All are about the same, but 2 and 3 are the best -- the most accurate.