During your entire educational career, teachers have probably told you the same, shopworn motto: Deep Understanding is more important than Memorizing Facts. You always knew that this was silly—those teachers would invariably test you on facts, and if you didn’t know them, then a “deep understanding” of them was impossible. That’s as true on the GMAT Quantitative section as it was in high school history.
Of course, GMAT Math questions primarily test your ability to solve problems, read problems critically, and draw upon the fundamental concepts of arithmetic, algebra, and geometry. But it’s also a race against the clock, and certain types of calculations will appear again and again. You will have to simplify radicals. You will need to know the properties of even and odd numbers. One or more questions will require you to know common squares, or higher powers of 2 or 3. And, inevitably and inexplicably, you will need to know the ratios of the side lengths in 45-45-90 and 30-60-90 right triangles.
These are not conceptually difficult calculations. That doesn’t stop them from being terrible time sinks for unprepared GMAT students. If you have to re-derive the properties of even and odd numbers on test day, you’ve lost a minute. If you have to multiply out 16 X 16 instead of just knowing it cold (256), you’ve lost thirty seconds. If your conceptual foundation is pretty solid but your knowledge of facts is weak, you’re going to spend between 5-10 additional minutes on easy questions with procedural quirks. That means less time on the difficult questions, where that time is more valuable.
Invest in test day by memorizing basic math facts now.