The term "linear measurements" is another way of expressing a one-dimensional measurement, or the length of anything that can be represented by a line. Some real-world examples of linear measurements include the length of your stride, the height of a person or the width of a box. When adding and subtracting linear measurements, both measurements must be in the same unit.
Converting Units of Measure
Before you can do any math with linear measurements, verify that each measurement is expressed in the same unit of measure and convert them if necessary. If you have one linear measurement that's expressed in more than one type of units, such as feet and inches, convert into the smaller unit of measurement. For example, if you're asked to add the widths of box A that is 2 feet wide and box B that is 1 foot, 5 inches wide, convert both measurements into inches. There are 12 inches per foot, so box A is 2 x 12 = 24 inches wide, and box B is 12 inches + 5 inches, or 17 inches wide.
Adding and Subtracting
When you add two or more linear measurements, it doesn't matter which order you add them in. So if you were to add the widths of the aforementioned box A and box B, you could write the problem as 24 inches + 17 inches, or as 17 inches + 24 inches; in either case you get the same answer: 41 inches.
To subtract, you must always write the larger number first. In this case, the difference in the widths of box A and box B is 24 inches - 17 inches = 7 inches.
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