3.3.8 More Division Strategies
Admittedly, division is usually more difficult than multiplication, but you can help yourself by having a good knowledge of the multiplication tables. In addition to this there are some other approaches we might use when dividing to help.
1. Using Groups of the Divisor
One way of looking at division problems is to see the problem as a question about the number of groups. For example, if the problem is , you may think, “How many groups of 13 are in 159?”
This approach uses multiplication to create groups of the divisor, keeping track of what part of the dividend remains. You may think about ten groups of 13, or . Next, you would subtract 130 from 159 mentally, leaving 29. Recognize that two more groups of 13 can “fit” into what remains, accounting for 26 more with only three left over. So 13 goes into 159 a total of times, with three left over. To check that, multiply , and . Bravo!
2. Breaking the Dividend into Parts
In this strategy, think about the dividend first, and how it can be broken up into numbers that are easier to divide by the divisor. For example, for the problem , you could think: “How can I break 159 apart to make this an easier problem to solve?”
You might think of this as:
Of course, there are many other strategies. Let’s look at two more that you might find useful in different situations.