Test-Taking Strategies

12: Math or Figure Series Test Problems

12 Math or Figure Series Test Problems Some test-takers seem to be born knowing how to whiz through these IQ puzzlers which give you a series of numbers, geometric figures, or letters and tell you to supply a missing part of the series-either at the end or somewhere in the middle. The rest of us have to attack such problems with a system that gets us the maximum number of points. These tests are nonverbal. They try to measure your ability to reason instead of your ability to work with words. But the same strategies that can help you pick up extra points on word reasoning tests will help you with math or figure series tests. STRATEGY 1: UNDERSTAND WHAT IS CALLED FOR Sometimes the directions seem terribly complicated. That's probably because verbal ability is not a requirement for people who prepare these tests. But, almost invariably, what you're supposed to do is: (1) figure out the rule used to 67 68 TEST-TAKING STRATEGIES create the series of numbers, letters, or shapes, and then (2) use that rule to figure out which number, letter, or shape comes next (or is missing along the way). When you try to make sense out of the directions on these tests, you'll save time if you start by assuming that they follow the general rule we have just given. Then read carefully to make sure that they do not deviate from the rule. STRATEGY 2: GUESS FIRST Since your hunches are usually right when you take tests such as these, take a good guess at the answer first. But check your hunch: plug your choice into the series and make sure that the rule carries through. If you have to supply a missing number (or other part) in the middle of a series, don't just test whether or not the rule applies from the beginning to your choice; also keep going from your choice to the end. STRATEGY 3: LOOK FOR SIMPLE PATTERNS In number series, the relationship or pattern you must find generally will be one of these: • addition • subtraction • multiplication • division • squaring • cubing • taking square root • taking cube root (occasionally) To complicate your life, some series use more than one of Math or Figure Series Test Strategies 69 these operations at a time. For example, this series uses two rules: I 4 25 676 In studying the series, you should notice right away that the numbers increase very quickly; they increase almost geometrically. That should be a clue that the rule probably involves squaring or cubing. But I squared or cubed is still 1. So you would have to start figuring out what rule was used in addition to squaring. Add I to I and then square the 2; that results in 4. But don't stop there. See what you get if you add I to 4 and then square the 5. Right! You get 25. Add I again, square again, and you get 676. So that's the rule. All you have to do next is add I to 676 and square the 677, giving the correct answer of 458,329. The same rule applies to letter series: look for simple arithmetic patterns. Look at this example: c f i lor If these were numbers instead of letters, you would have the answer in a second. Don't let the letters throw you. Run down the list of simple math procedures: addition, subtraction , multiplication, division. Here you'll stop at addition, since the letters progress by threes. The next letter should be u. STRATEGY 4: LOOK FOR SUBPATTERNS AND SUBGROUPINGS If you've found a pattern that works for all but a few numbers or letters, start looking for subgroupings that, 70 TEST-TAKING STRATEGIES taken as units, follow another rule. The following is an example: 2 5 11 22 45 91 205 To get 5 and 11, you double the previous number and add 1. To get 45 and 91 you double the previous number and add 1. But 22 and the missing number break that pattern, so you must look for a second pattern to add to the first one. An average student might look for a relationship between 2 and 22 and search the answer choices for 222 or 42 (one or both of which may be there to stump the unwary). But the testwise student knows that...