Math Strategy: Plugging In

May 3, 2012 by Yolanda Fontanez-Coleman | Math, SAT Prep, Testing

Math sections on the SAT or ACT can be a bit overwhelming at first, however plugging in the multiple choice answers can help!  Here’s a hint: the multiple choice answers are always in hierarchical order, therefore it is important to use this to our advantage!  To do so, we must always always always start plugging in choice C.  By starting with choice C, this allows you to gauge whether the correct answer is smaller or larger than choice C.  If it is smaller, then you are only plugging in choices C, B, and A to figure out the correct answer.  Vice versa, if it is larger, then you are only plugging in choices C, D, and E to figure out the correct answer.  This cuts down on the time it takes you to answer the question, and also decreases test anxiety as you are not overwhelmed with an enormous amount of work to do!

SAMPLE PROBLEM:

If x²  = 2x – 1, then x equals

1. -2
2. -1
3. 0
4. 1
5. 2

So you may choose to solve this problem using your algebra skills manipulating the question using the variables and such, or you may choose to plug in a number from the multiple choice selections.  As stated earlier, start with C.  This allows you to simply plug in 0 wherever there is an X, therefore (0)² = 2(0) – 1, which when solved, 0 = -1.  As well as know, 0 and -1 are two different numbers that do not equal each other, however the difference between the two numbers is 1 so we need to choose a higher number.  This leads us to plug in the number 1 wherever there is an X, which is multiple choice D, therefore (1)²  = 2(1) – 1, which when solved, 1=1.  Since the number 1 does equal itself, we have figured out that answer choice D is the correct answer.  We have saved time by only plugging in 2 out of the 3 multiple choice options and are not overwhelmed completing numerous math problems in order to find the correct answer.

Blog submitted by Meredith Mathers, Team Tutor Test Prep Specialist 

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