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In<\/span> my last blog post,<\/span><\/a> I had a chat with my dad, a math teacher, about the importance of mental math. Today, I want to get more specific: I want to give you some things to memorize before you take the GMAT or GRE, along with a few tips about how to practice memorizing them.<\/span><\/p>\n <\/p>\n What:<\/b> Times tables up to 12 (and practice your multiplication and division in general)<\/span><\/p>\n Why:<\/b> You\u2019ll be doing these calculations so often during the test that errors will destroy your score and cost you time. When my students complain that they make too many \u201csilly mistakes,\u201d one of the first things that I ask them is, \u201cWhat\u2019s 12 times 7?\u201d If you can\u2019t answer that quickly, then not only have you identified the problem, you\u2019ve also learned that the solution to your problem is a relatively low-effort one.<\/span><\/p>\n How:<\/b> (1) Make flashcards! And don\u2019t use a flashcard app; there\u2019s some evidence that writing the flashcard yourself will help you memorize it. (2) There are endless opportunities in everyday life to practice your times tables: my suggestion is to just stop using your calculator when your brain will do. Need to buy eight pizzas at $9 each for your little sister\u2019s soccer team? Figure out the total in your head. Need to split that total among 6 team parents? Put that calculator app away, cheater \u2013 you can do that on your own now! Got an option to pay your car insurance in a lump sum vs. 12 monthly payments? Figure out how much more the monthly option is going to cost you. Bored at the gas tank? Check your odometer at two fill-ups in a row, and figure out what kind of mileage your car <\/span>actually<\/span><\/i> gets (vs. what the slick car ad copy promised). There are endless opportunities out there as long as you stay curious.<\/span><\/p>\n What:<\/b> Fraction-percent conversions for 1\/2, 1\/3, 1\/4, 1\/5, 1\/6, 1\/8, 1\/9, 1\/10, 1\/20, and 1\/100.<\/span><\/p>\n Why:<\/b> Because these conversions lead to many other conversions (for example, 1\/9 is 11.1%, so 7\/9 is 77.7%). Also, a problem that is difficult in decimal\/percent form can become infinitely easier in fraction form, and vice versa. Want proof? What\u2019s 37.5 percent of 560? Easy: it\u2019s 3\/8 of 560. So divide by 8 to get 70, then multiply by 3 to get 210.<\/span><\/p>\n How:<\/b> Remember that pizza for your little sis? What\u2019s the delivery charge going to be if you want to give the delivery person a 15% tip? (Just take 1\/10 of the total, then half of that, and add those two numbers together). Want to buy that flat screen TV at Costco, but worried about the 9% sales tax? Just divide the price by 11 and tack it on. Here\u2019s one of my personal favorites: every time you see some item on sale for some percentage off, figure out what it actually costs, and then immediately find something else that you wanted recently that you could buy at full price for roughly that same amount of money. Then you\u2019ll know whether you\u2019re really getting a deal. Oh, also: tip charts are the new answer keys. Figure out the tip yourself first, then check to make sure you\u2019re right!<\/span><\/p>\n What:<\/b> Prime numbers up to 100<\/span><\/p>\n Why:<\/b> Because most big numbers are just a bunch of smaller prime numbers multiplied together. I saw a GMAT problem where a crucial final step was to add 1\/15 + 1\/18. Far too many of my students thought that they needed to convert the denominator to 270. But the ones who found prime factors of 15 (3 \u00d7 5) and 18 (2 \u00d7 3 \u00d7 3) noticed that both 15 and 18 contain a 3, so 90 is actually the common denominator; those students, on average, solved the problem about a full minute faster. Also, some GMAT problems ask you quite directly whether a number is prime. Why not just memorize some primes in advance?<\/span><\/p>\n How:<\/b> For all positive integers from 2 to 100, a number is prime if it\u2019s not divisible by 2, 3, 5, or 7. So just start learning primes in the shower; see if you can get to 100 without missing any. Conveniently, this will also teach you shortcuts for how to check whether a number is divisible by 2, 3, or 5 (there\u2019s no great shortcut for 7, so see \u201ctimes tables,\u201d above!).<\/span><\/p>\n What:<\/b> Powers of 2 (2, 4, 8, 16, 32, 64, 128, 256, 512)<\/span><\/p>\n Why:<\/b> Because you\u2019ll need to be able to recognize them on sight, not to mention that it\u2019s important if you want to keep the respect of your IT team. The GMAT and GRE will ask you to simplify expressions like 32^5 \u00b7 64^3. This is impossible without knowing that 32 is 2^5, and 64 is 2^6.<\/span><\/p>\n How:<\/b> Do a web search for \u201c2048\u201d \u2013 it\u2019s a surprisingly addictive web-based game; if your boss catches you playing at work, don\u2019t say I didn\u2019t warn you.<\/span><\/p>\n Learn the two most common Pythagorean Triples (3-4-5 and 5-12-13), the ratio of sides in a 45-45-90 triangle and a 30-60-90 triangle, the decimal approximations (to a tenth) of \u221a2, \u221a3, and \u03c0, powers of 3 (notice I said \u201cpowers,\u201d not \u201cmultiples\u201d), factorials from 2! to 6!, and how to factor the difference of squares. If you show up to the first day of my GMAT class with everything in this post down cold, I promise it will not only enrich your experience in class, it will also help you achieve the best score possible!<\/span><\/p>\n RELATED: <\/b>Common Math Errors on the GMAT<\/span><\/a><\/p>\n You can attend the first session of any of our online or in-person GMAT courses absolutely free! We\u2019re not kidding. <\/i><\/b>Check out our upcoming courses here<\/i><\/b><\/a>.<\/i><\/b><\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n","protected":false},"excerpt":{"rendered":" In my last blog post, I had a chat with my dad, a math teacher, about the importance of mental math. Today, I want to get more specific: I want to give you some things to memorize before you take the GMAT or GRE, along with a few tips about how to practice memorizing them.<\/p>\n","protected":false},"author":25,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[52871],"tags":[319,52785,325],"yst_prominent_words":[57515,57518,53790,57516,57514,57490,57492,53635,57525,57524,57526,53997,57508,57340,57330,57505,55065,57517,53704,57339],"class_list":["post-18623","post","type-post","status-publish","format-standard","hentry","category-gmat-strategies","tag-gmat-quant","tag-gmat-quant-strategies","tag-gmat-quant-tips"],"_links":{"self":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts\/18623","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/users\/25"}],"replies":[{"embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/comments?post=18623"}],"version-history":[{"count":5,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts\/18623\/revisions"}],"predecessor-version":[{"id":18632,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts\/18623\/revisions\/18632"}],"wp:attachment":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/media?parent=18623"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/categories?post=18623"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/tags?post=18623"},{"taxonomy":"yst_prominent_words","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/yst_prominent_words?post=18623"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}What to Memorize for GMAT Quant\u00a0<\/b><\/h3>\n
GMAT Mental Math Tip 1:<\/h4>\n
GMAT Mental Math Tip 2:<\/h4>\n
GMAT Mental Math Tip 3:<\/h4>\n
GMAT Mental Math Tip 4:<\/h4>\n
Honorable Mention Tips:<\/h4>\n
\n![\"ryan-jacobs\"](\"https:\/\/cdn2.manhattanprep.com\/gmat\/wp-content\/uploads\/sites\/18\/2018\/02\/ryan-jacobs-e1501597417957-150x150.png\")
Ryan Jacobs<\/a>\u00a0is a Manhattan Prep instructor based in San Francisco, California.<\/strong>\u00a0He has an MBA from UC San Diego, a 780 on the GMAT, and years of GMAT teaching experience. His other interests include music, photography, and hockey.\u00a0Check out Ryan\u2019s upcoming GMAT prep offerings here<\/a>.<\/em><\/p>\n