Answer:
It is sometimes called the factor label approach because units are treated as a factor (along with a numeric factor) in a quantity like 25 g, allowing us to subject the unit to algebraic operations as if they were variables.
Step-by-step explanation:
It is sometimes called the factor label approach because we can treat a quantity like 25g as a product of a numerical factor and a unit factor, allowing us to subject the unit to arithmetic operations as if they were variables. Dimensional analysis can be most helpful when helping to set up a problem involving multiplication or division, but it is not limited to multiplication and division: Adding or subtracting quantities, for example, requires they have the same unit, just like adding algebraic terms 5x and 6x, and this rule can be used to help set up or check a calculation.