Below is the transcript of my YouTube tutorial video MCAT Math Video #1 – Introduction To Math Without A Calculator. (click to watch this video on YouTube)
Leah here from leah4sci.com/MCAT and in this video series I’m will teach you how to do MCAT Math without a calculator. As part of MCAT you will have to answer Math related questions especially when it comes to Physics and General Chemistry but you’re not allowed to use calculator. Does this mean that they’ll ease up at you where the Math is related? Heck no! And so, to learn how to answer these questions and still save time to make sure you’ll get through the section, you will have to learn the following:
- You have to learn how to do the required Math by hand or better yet in your head and
- You have to know WHEN and WHAT type of shortcuts to use so that your answer is good enough
Over the next few videos I’ll take you through the different types of Math problems and show you the MCAT shortcuts that you can use. You can find my entire series on MCAT Math Without a Calculator by visiting my website http://leah4sci.com/MCATMath.
So how it is they allow to use shortcuts in the MCAT? Well here’s the thing, They’re not testing your Math skills, remember this is a Science test, instead they’re testing to see if you understand the information, if you know how to apply logic and reasons through questions and most importantly if you know which formulas to use and how to apply them. So when you look at the answer choices you’ll see that the numbers are not very close to each other, in fact some of them will be radically different. This means that if you know how to do the correct Math and get some version of the right answer or better yet something close enough, you’ll be able to rule out the wrong choices and quickly get your answer without significance or long complicated Math equations. This means you’ll have to learn where to round, where to simplify and what type of shortcuts to take.
For example, you may be given a question like this: “How many moles of Chlorine Ions are found in 4.93L of a 0.096 molar solution?” – My MCAT Math tricks will help you to deuce that the answer is close to 0.5moles of Chlorine Ions in under 10 seconds! Punching this into the Calculator I get a value of 0.47328 which is close enough to 0.5. Because if this was your MCAT question, your choices will range in the multiple decimal or multiple figures for the answer.
If you find yourself working through the Math this way, DON’T! Not only you’re wasting so much time, but notice I even have a careless mistake. I have 0.472286, the answer should be 0.47328, so I miss the number here somewhere. And the reason I left it on the video is to prove to you that not only is this a waste of time but under pressure you are bound to make careless mistakes. Now say you did do this, the careless mistake still gives us the answer close enough. But how did I get the initial answer of 0.5 moles in under 10 seconds? These are the very tricks I’m going to show you piece by piece in the upcoming videos.
But let’s take a look: The first step is to round and simplify where possible. Our question is (4.93 x 0.096). The first thing we want to do is simplify this; 4.93, 4.9 that’s very close to 5 so I’m gonna round the number up to 5. 0.096, 96 is close to a hundred, so if I replace these numbers to a hundred (100), what I’m really looking at is 0.1. Now I have a much simpler problem to solve and that’s (5 x 0.1), as you’ll soon learn with decimals, we’d simply approach this as (5×1) which is 5. We have 1 decimal space to the left in the example which means we move the answer back 1 space. Now, I wrote this out to show you what I did, but with enough practice you actually do this in your head and it should take less than 10 seconds to come up with the answer of 0.5 moles.
What happens when the choices given are very close to each other? Let’s say with this example we have 4 choices, 2 of which are so extreme we were able to rule them out. But now we’re left with 0.47 moles as one choice and 0.53 moles is the second. Remember we set our answer very close to 0.5 but 0.5 is equidistant from 0.47 to .0.53, we still don’t have to go back and do the detailed Math, instead we want to analyze how we got the shortcut and see how that can help us guesstimate the correct answer.
Once again going back to our choices, 4.93 was rounded up to give us 5. 0.096 was rounded up to give us 0.1 that means our answer of 0.5 is slightly rounded up from the correct answer. Looking at the 2 choices, we don’t want the answer that’s even higher to the answer we rounded up, instead we want the one that’s slightly lower to compensate for the fact that we rounded up. In other words, we rounded our answer up now we need to bring it back down to get the correct answer and that’s how we estimate 0.47 and still haven’t spent more than 20 seconds in the entire thing.
Now before continuing to the next video, I wanna leave you with few things, FIRST: You have to be very comfortable with your Basic Math. This includes Multiplication of Standard Numbers, this includes the value of fractions and more. If you’re not comfortable with this or don’t know what to memorize, visit my website to download my FREE MCAT Math Study Guide and you can find this at http://leah4sci.com/MCATMATH.
Let me show you another trick. When it comes to Math, don’t only rely on the calculations that you know how to do or you memorize. Try to think outside the box and see how you can twist or manipulate numbers to solve questions. For example: Say I ask you to perform the calculation 25 x 7 in your head. The average student looks at me like I’m crazy, I don’t know how to do that!
But now think about this, 25 cents is the value of a quarter. If you had 7 quarters how much money are you holding? Some of you can do this in your head and say Wow! 7 quarters that’s a dollar and 75! Meaning our answer is 175. But if you’re not sure, break it up! 7 quarters has 4 quarters for the first dollar, that’s 1 or a hundred. 3 quarters remain at a value of 75 cents that’s a dollar 75 or a hundred seventy five (175). Noticed we went on the traditional wrap relating it to something that we know for example MONEY! Quarter, Nickels, Dimes, those are very helpful when it comes to Math and then we apply it back to our questions.
Be sure to join me in the next video where I take you through Multiplication and Division tricks showing you the Decimal trick that I applied here and so much more!
Are you stuck on a specific MCAT topic? I offer Private Online Tutoring where I focus on your needs to strengthen your individual weaknesses. Tutoring details can be found using the link below or by visiting my website leah4sci.com/MCATTutor.
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Watch the video here: MCAT Math Video #1 – Introduction To Math Without A Calculator