Improving your speed and accuracy on relatively simple arithmetic and algebra will increase your chances of achieving a top quant score on the GMAT. Yes, the exam is primarily designed to test your reasoning skills, but since time is a major factor, shoring up these core skills may help you perform more efficiently and consistently, thereby freeing up that little bit of extra time you need to let your reasoning skills shine and achieve a significant breakthrough.
How much of a difference can this make? I think it can be huge. Many times when I work with people who have already done a great deal to prepare for the exam, I am impressed by the speed with which they can do the conceptually difficult parts of a problem. But they’ll take an additional 30 seconds or more to do a few simple arithmetic or algebraic manipulations, and even more tragically, they will sometimes make errors on these tasks.
You can often save time if you are skilled at what I call the three F’s: fractions, factoring and FOILing (First, Outside, Inside, Last = distributing expressions). Are you confident in adding, subtracting, multiplying and dividing fractions? Can you quickly convert common decimals and percentages to fractions and vice versa? Do you recognize when to factor or FOIL?
Here’s an arithmetic example. Do you know how to simplify the expression on the right? Did you convert the 3 to 3/1 and then multiply 2/7 by 1/3? If so, that’s good, but here’s a shortcut: when a fraction is divided by a whole number, the numerator of the fraction stays the same and the denominators are simply multiplied together. So in this case, 2 stays in the numerator, and the denominator becomes 7×3 = 21. You can apply the same concept to algebraic expressions to save time, too.
So if you find your core skills lacking, you might find that devoting some prep time to relatively easy arithmetic and algebra drills will improve your consistency, confidence and scores more than tackling another advanced quant book.