![\"Manhattan](\"http:\/\/www.manhattanprep.com\/gmat\/wp-content\/uploads\/sites\/18\/2017\/04\/fast-math-gmat-part-2-koprince.png\")
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Did you know that 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><\/span><\/p>\n Welcome to part 2 of our Fast Math series! In Part 1<\/a>, I acquainted you with the fact that I\u2019m a lazy math person: I don\u2019t want to do any more than I have to in order to answer the question. And this series shows you how! <\/span>\u263a<\/span><\/p>\n You already saw the first example of this in Principle #1: <\/span><\/p>\n Shortcut #1:<\/span><\/i> When multiplying a string of numbers, pair off the 5\u2019s and 2\u2019s and multiply them first.<\/span><\/p>\n What if that last problem in part 1 hadn\u2019t<\/em> had a 20 in it? If you had to multiply 5 and 81\u2026how would you do that?<\/span><\/p>\n You could do long multiplication, of course. But ugh\u2026don\u2019t do that.<\/span><\/p>\n There are various shortcuts for multiplication, but here\u2019s my favorite one specifically for multiplying by 5:<\/span><\/p>\n Take the non-5 number (in this case, 81) and <\/span>halve<\/span><\/i> it: 81 <\/span>\u2192<\/span> 40.5<\/span><\/p>\n Move the decimal one place to the <\/span>right <\/span><\/i>to make it bigger<\/span>: 40.5 <\/span>\u2192<\/span> 405<\/span><\/p>\n Done!<\/span><\/p>\n Shortcut #2:<\/span><\/i> To multiply by 5, first <\/span>halve<\/span><\/i> the other number, then make it bigger again by moving the decimal one place to the <\/span>right<\/span><\/i>.<\/span><\/p>\n Really. That\u2019s it. Try it again: what is 5 <\/span>\u00d7<\/span> 37?<\/span><\/p>\n I don\u2019t know about you, but this one\u2019s a bit harder for me to divide by 2. The number 36 divided by 2 is 18\u2026ah, so 37 divided by 2 must be 18.5.<\/span><\/p>\n Finally, move the decimal one place to the right to make it bigger: 18.5 becomes 185.<\/span><\/p>\n Shortcut #<\/span><\/i>3<\/span><\/i>:<\/span><\/i> If division involves an annoying number<\/span> (eg, 37)<\/span>, start from a nearby easier number<\/span> (eg, 36)<\/span> and then work to the annoying number from there.<\/span><\/p>\n What if you need to divide<\/em> 81 by 5 instead? Check it out:<\/span><\/p>\n Take the non-5 number (in this case, 81) and <\/span>double<\/span><\/i> it: 81 <\/span>\u2192<\/span> 162<\/span><\/p>\n Move the decimal one place to the <\/span>left <\/span><\/i>to make it smaller<\/span>: 162 <\/span>\u2192<\/span> 16.2<\/span><\/p>\n Try it again: what is 896<\/sup>\u20445<\/sub>?<\/span><\/p>\n Hmm. 900 <\/span>\u00d7<\/span> 2 = 1,800, so 896 is 4 \u00d7 2 = 8 less than that: 1,800 \u2013 8 = 1,792.<\/span><\/p>\n Then, move the decimal one place to the left to make the number smaller: 1,792 <\/span>\u2192<\/span> 179.2.<\/span><\/p>\n Shortcut #4:<\/span><\/i> To divide by 5, first <\/span>double<\/span><\/i> the other number, then make it smaller again by moving the decimal one place to the <\/span>left<\/span><\/i>.<\/span><\/p>\n What do you think so far? We\u2019re just getting started; next time, we\u2019ll dive into Principle #3<\/a>. And start looking for other Fast Math opportunities during your studies!<\/p>\n KEEP READING:\u00a0<\/strong>FAST Math for the GMAT (Part 3)<\/a><\/p>\n Can\u2019t get enough of Stacey\u2019s GMAT mastery? Attend the first session of one of her upcoming GMAT courses<\/a> absolutely free, no strings attached. Seriously.\u00a0<\/strong><\/em><\/p>\n Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We\u2019re not kidding! Check out our upcoming courses here. Welcome to part 2 of our Fast Math series! In Part 1, I acquainted you with the fact that I\u2019m a lazy math person: I […]<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[873,929,52871,930,2,8],"tags":[53022,53023,283],"yst_prominent_words":[57233,57227,57232,53868,53779,56861,57230,57228,57221,53635,53781,53775,56857,57229,57231,54189,57226,57225,53784,53867],"class_list":["post-13686","post","type-post","status-publish","format-standard","hentry","category-for-current-studiers","category-gmat-prep","category-gmat-strategies","category-gmat-study-guide","category-how-to-study","category-quant-on-gmat","tag-fast-math","tag-fast-math-for-the-gmat","tag-gmat-math"],"_links":{"self":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts\/13686","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\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/comments?post=13686"}],"version-history":[{"count":10,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts\/13686\/revisions"}],"predecessor-version":[{"id":19606,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts\/13686\/revisions\/19606"}],"wp:attachment":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/media?parent=13686"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/categories?post=13686"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/tags?post=13686"},{"taxonomy":"yst_prominent_words","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/yst_prominent_words?post=13686"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nPrinciple #2: Learn shortcuts for when you do have to do the math.<\/b><\/h4>\n
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\n![\"stacey-koprince\"](\"https:\/\/cdn2.manhattanprep.com\/gmat\/wp-content\/uploads\/sites\/18\/2015\/06\/stacey-koprince-150x150.png\")
<\/a>Stacey Koprince<\/a> is a Manhattan Prep instructor based in Montreal, Canada.<\/strong> Stacey has been teaching the GMAT, GRE, and LSAT \u00a0for more than 15 years and is one of the most well-known instructors in the industry. Stacey loves to teach and is absolutely fascinated by standardized tests. Check out Stacey\u2019s upcoming GMAT courses here<\/a>.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"