Читать книгу All the Math You'll Ever Need - Steve Slavin - Страница 26

Division is the opposite, or inverse, of multiplication. You can think of a division question like 21 ÷ 3 = ? as the related multiplication question 3 × what = 21? Sometimes memory is enough to answer that. You can also phrase the question as, “If you put 21 objects into groups of 3, how many groups can you make?” Another approach is to ask, “If 3 people share $21, how much does each person get?”

Division with larger numbers can get complicated. There are several methods, one of which is covered below. Others will come up in Chapter 4, “Focus on Division.” It's fair to say that division with larger numbers is one task for which calculators are helpful. If you're going to use a calculator, you'll want to be able to estimate the answer, so that you can see if the answer on the calculator is reasonable. Errors, even as simple as a typing error, can give you a wildly wrong answer.