Cooking math help on fractions... thanks?!

remember your gradeschool fraction math?

Here's mine: multiply each you've entered by 2/3...
18 * 2/3 = 36/3 or 12. so you've entered 12 cups of flour.
5 * 2/3 = 10/3 or 3 1/2 ...
2 *2/3 = 4/3 or 1 1/3 ...

I have that you've entered:
12 cups flour
3 1/3 cups sugar
1 1/3 cups milk

Given that, and you want to get to the original recipe:
18 - 12 = 6
5 - 3 1/3 = 1 2/3
2 1/4 - 1 1/3 = pure math is 11/12 cup. 11/12 of 1 cup is the same as (1) 2/3 cup + (1) 1/4 cup

So:
add 6 cups flour
add 1 2/3 cups sugar
add 2/3 cup milk AND also add 1/4 cup milk

you poured 12c you need 6 more of flour
you poured 3.333c sugar and you need 1.67 more
you poured 1 1/3 of dry milk and you need .92 more

This is one reason it's so much easier to do recipes with weights rather than volumes--ounces or grams are a lot easier to measure accurately, especially with a good scale! LOL

I'll let you use the math that the others provided. But I'd like you to make sure you actually used a 2/3's cup measure. I've never seen a set of measuring cups that included one for 2/3 - only 1/8, 1/4, 1/3, 1/2 and 1 cup for dry measuring cups.

Add:
18 1/3 cups flour, or 6 cups
5 1/3 cups sugar, or 1-2/3 cups
You already have too much dry milk; it shouldn't hurt the recipe.
Learn to notice the size of measuring cups! :-)

ON EDIT: Oops! twobluec... is correct on the dry milk.

18*.66=11.88
18(-)11.88=+6.12C=6- 1/8C
<<<<
5*.66=3.3
5(- )3.3 =+1.7 C= 1 -2/3 C
>>>
2 * .66=1.32
2.25 (-) 1.32 =+.93C= 7/8 C

Flour: 18 x 2/3 = 12 cups poured You need 6 more cups

Sugar: 5 x 2/3 = 3 1/3 cups poured You need 1 2/3 more cups

Non fat milk: 2 x 2/3 = 1 1/3 cups poured You need 11/12 more cups

18 cups flour - I poured 18 - 2/3 cups =6
5 cups sugar - I poured 5 - 2/3 cups =1 3/4
2 1/4 cups dry nonfat milk - I poured 2 - 2/3 cups =3/4