There are 36 ounces in 4.5 cups. If you are using imperial measure a large imperial (1.25) cup has ten ounces {half pint} and 4.5 of these cups would have 45 ounces.

I assume you mean 4 and a half fluid ounces, not 4 and a half weight ounces. A cup has 8 ounces. Therefore 4 and a half ounces is 4.5/8 cups. 4.5/8 = 45/80 = 9/16 = 0.5625 cups

Divide the total ounces by the number 8 to get the number of cups. 8 liquid ounces = 1 cup. There are 64 ounces in a 1/2 gallon or 8 cups and 128 ounces in a gallon, or 16 cups.

1 cup = 8 fluid ounces 2 cups = 16 fluid ounces. If you're talking about ounces of weight, then it depends on what substance you have 2 cups of. If the 2 cups are empty, then the weight is zero ounces.