If 1 cup of chocolate chips weighs about 6 ounces
The recipe calls for 3 1/4 cups of chocolate chips.
We need to multiply 6 by 3 which is 18 ounces plus the 1/4 which is 6 times 1/4 = 1.5 ounces
18 + 1.5 = 19.5 ounces of chocolate chip needed