What is two thirds cup doubled? 2/3 of a cup doubled is 1 and a half cups. 11 people 3/4 of a cup doubled is 6/4 of a cup, which equals 1 1/2 cups. 6 people.
Two-fold, three-fold, etc., can be equated to doubled, trebled, or to for instance, if the final amount is not a whole number multiple (like 2, 3.
I don't bother to do the math. If I am doubling a recipe, I just put everything in twice. For some recipes, it's better to make two separate batches.
2//3 doubled is - players only