Mario has 7 cups of milk. A one batch recipe for pancakes calls for 2/3 cup milk. To see how many batches he could make Mario finds 7 divided 2/3. He said 7 divided 2/3=1/7 x 3/2 he could make 3/14 of a batch. Where is the error

Mario's mistake is made when doing reciprocal.

7 / (2/3) =

I cannot divide by 2/3, but if I do reciprocal, I can multiply by 3/2. The seven comes first, so it should not be flipped.

Mario's mistake was when he flipped the 7 (or 7/1) to 1/7.