Three quarter cups are needed to make three-quarters of a cup. When something is divided into quarters it is separated into four equal parts. Therefore, there will always be four quarters for every cup.
If you wanted 3/4 cup of sugar but only have a 1/4 measuring cup, simply add 1/4 cup three times. It would look like this: 1/4 + 1/4 + 1/4 = 3/4. Another way to look at this equation would be through subtraction. If you have 1 cup but would like 3/4 cup, subtract 1/4 cup from 1 cup. That looks like this: 1 - 1/4 = 3/4.