Читать книгу Algebra I All-in-One For Dummies - Mary Jane Sterling, Mary Sterling Jane - Страница 81

Before you can add or subtract fractions, you need to find a common denominator for them. Ideally, that common denominator is the least common multiple (the smallest number that each of the denominators can divide into without a remainder). A method of last resort, though, is to multiply the denominators together. Doing so gives you a number that the denominators divide evenly. You may have to work with larger numbers using this method, but you can always reduce the fractions at the end.

And then, there’s the box method. This method is especially helpful when you have three or more fractions to deal with — and they have relatively large denominators.