By performing one simple task, you can eliminate two of the possible
answers. Multiply the last digits in each number (1 3). The answer
must end in 3. So (A) and (B) have been eliminated...that fast!
Now, eyeball (C) and (D). Can you find the right answer quickly?
Here you are doing educated guessing, known in math circles as
“guesstimating.” Look: 281 100 is 28,100. You should be able to
do that without any tools. Therefore, (D) has to be wrong. You are
left with (C).
Should you do the actual math to double-check your answer?
I wouldn’t. You are certain that (A) and (B) are wrong. Absolutely.
You know that (D) is much too high. Mark (C) as the answer and
move on.
Here are other ways to better your score on math tests:
■ Try to figure out what is being asked, what principles are
involved, what information is important, and what’s not. Don’t
let extraneous data throw you off track. Make sure you know
the kind of answer you’re seeking: Is it a speed, weight, angle,
exponent, square root?
■ Whenever you can, “translate” formulas and numbers into
words. Estimate the answer before you even begin the actual
calculation. At least you’ll know the size of the ballpark you’re
playing in!
■ Even if you’re not particularly visual, pictures can often help.
Try translating a particularly vexing math problem into a
drawing or diagram.
■ Play around. There are often different paths to the same
solution, or even equally valid solutions.
■ When you are checking your calculations, try working
backwards. I’ve found it an easier way to catch simple
arithmetical errors.Chapter 8 ■ How to Study for Tests 199