When units of measure undergo mathematical operations the first thing you must identify are the units of each measure. If the units are not the same, you must first convert both values into the same measurement scale. This is why in most cases this skill is a two-part problem. Remember that when we working with fractions of different denominators; it is helpful to get both denominators in the same form.

When you have two measurements in the form of fractions, and you want to add or subtract them, you need to recall the way you used to solve normal fractions. There are two types of fractions that you will have to deal with, and these are proper and improper. To add or subtract fractions, you need to make the denominators the same. Without this, you cannot add or subtract these fractional measurements. Consider this; you measured an item which measured 2 1/2 and another object which measures 2 3/4. Now, you want to add these measurements. What you need to do is, make the denominator the same, add the fractions, and then the whole numbers. If you get an improper fraction, you can change it into a mixed number and simply add the two whole numbers together. Summing up these two gives you, 4 5/4 and when you turn the improper fraction into a proper fraction, the final answer becomes 5 1/4. These worksheets explain how to add and subtract fractional forms of measurement units, such as gallons and quarts or pounds and ounces. Some answers will include mixed numbers.