MCAT and Organic Chemistry Study Guides, Videos, Cheat Sheets, tutoring and more

  • Tutoring
  • Organic Chem
    • Organic Chemistry Videos
    • Organic Chemistry Tutoring
    • Study Hall – Membership Site
  • MCAT
  • About
  • Contact
  • Tutoring
  • Organic Chem
    • Organic Chemistry Videos
    • Organic Chemistry Tutoring
    • Study Hall – Membership Site
  • MCAT
  • About
  • Contact

Video Transcript : Multiplication and Division for Units of Ten

July 31, 2014 By Leah4sci

mcat math trick for multiplication and division using units of 10Below is the transcript of my tutorial video Multiplication and Division for Units of Ten

(Click here to watch on YouTube)

[Start Transcript]

Leah here from leah4sci.com/MCAT and in this video I will show you how to quickly and easily Multiply and Divide numbers by a factor of 10 without a calculator.

You can find my entire series on doing MCAT Math Without A Calculator by visiting my website https://leah4sci.com/MCATMATH.

Multiplying and Dividing by factors of 10 will come up again and again in your MCAT practice including questions related to everything, from Unit Conversions to General Math. Multiplying and Dividing by 10 is a fun way to do Math in your head and 10 comes up in a lot of questions from converting something like grams to kilograms, solving gravitational acceleration questions and so much more. Or say your number does not have the factor of 10, round it to the nearest 10 and then apply the tricks. Why? Because it’s easier and faster than doing it the long way.

Now before I show you how to find the solution of 3.47 x 1000 in under 5 seconds, let’s do a fun exercise. Say I ask you to perform the calculation of 2.3 x 10 in your head. Some of you can do it, others will look at me like I’m crazy! Now maybe I am, but that’s not the topic for today. If you got it, great! If not, let’s try this quick exercise.

video2_scap1

If I ask you 1 x 10, I hope you know that the answer is 10. If you didn’t, you need to download my MCAT Math guide by visiting my website https://leah4sci.com/MCATMATH. Now if I ask you to do 2 x 10, the answer is 20. If I ask you to do 3 x10, the answer is 30. These are simple equations, but I want you to focus not on the answer but think about what you did.

You have a number and you multiplied it by 10 so all you did was add a zero. We took the number 3, we added the 0, that’s how we got 30. Now if I ask you to do 20 x 10, once again, all I do is add a zero (0), that gives me Two Hundred Thirty (230). In other words, to multiply any number by 10, all you have to do is add a zero (0).

So what if I ask you to do 2.3 x 10 or we can’t really add a zero because we have a decimal. So let’s revisit the initial trick; when we added a zero, all we really did was move that imaginary decimal at the end of the number over one space to the right. Starting with 1, we move it over that gave us 10, 2 gave is 20, 3 gave us 30 and 23 gave us 230.

video2_scap2

So if the decimal is not invisible, the same trick applies. Take the decimal, move it over one space to the right and 2.3 now becomes 23. Let’s crank it up a notch. What if I ask you to solve 37 x 100? We’re not dealing with 10 now we are dealing with a hundred (100) which is 10 x 10.

Anytime you have the number 1 followed by zeros (0), that number is simply 1 x 10 again and again until it equals the number of zeros that you have. Looking at the number 100 we have two zeros (0), that means we’re multiplying by two factors of 10 so we’ll take that imaginary decimal at the end of number and move it over 2 spaces, one for each zero giving me an answer of 3700.

Now let’s revisit our initial question. This may show up as part of a larger question asking you to convert 3.47 kilograms into grams. So we take our initial value of 3.47kg. I’m writing this out to show you but I want you to set this up mentally. Knowing that there’s a thousand (1000) grams every kilogram we set it up so kilograms can cancel and now our equation is simply 3.47 x 1000. A thousand has 3 zeros which means we move the decimals 3 spaces to the right – one, two, three, giving as an answer of 3470. This example when done in your head should take you under 5 seconds!

video2_scap3

Now let’s say we want to divide a number by a factor of 10. If multiplying by 10 means you move the decimal to the right, then dividing by 10 means you move the decimal to the left. Let’s start simple: 30 divided by 10, we take the decimal, move it one space to the left that gives us 3. Given 470 divided by 100, one hundred (100) has two zeros so we take the decimal move it 2 spaces to the left, that gives us 4.7.

Now what if you’re starting with the decimal? Say you have 0.53 and you want to divide it by 1000. For example you have 0.53 grams and you want to turn this into kilograms. We have three zeros dividing by 1 and three zeros means move the decimal three spaces to the left, one, two, three. Be very careful to count your zeros here, the answer is 0.00053. you’ll probably see this in Scientific notation and that’s something I will cover in the future video.

video2_scap4

Now what if the example given isn’t as clean, meaning you don’t see the 10 as obvious? So let’s make up a number; Say we have 3.29 and we want to multiply this by 9.73.  When 9.73 is very close to 10 and on the MCAT, close enough is good enough. 9.73 is 10 that means we move the decimal one space to the right giving me an answer of 32.9.

Remember the choices on the MCAT won’t be very very close to each other because they’re testing your ability to do the right kind of Math and give you wrong answers that are simply all over the place allowing you to rule out anything that is way too far off from the number that you got.

Be sure to join me in the next video where I take this concept to the next level, showing you how to quickly multiply and divide numbers using the factor of 10 trick when you can even round your number to the nearest 10.

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.

Are you overwhelmed by the sheer volume of information required for the MCAT? Are you worried that lack of a proper study plan and low MCAT score will prevent you from getting into Medical School? My new ebook The MCAT Exam Strategy is 6-Week Guide to Crushing the MCAT will help you formulate a concrete study plan by helping you figure out where you stand now, identify your goals and figure out what it takes to reach them and it’s yours FREE when you sign up for my email newsletter at MCATExamStrategy.com. By signing up for my email newsletter, you’ll also be the first to know when I have new videos, MCAT Study Guide Cheat Sheets Tips and so much more! The link again MCATExamStrategy.com.

[End Transcript]

Watch The Video Here: MCAT Math Trick – Multiplying and Dividing Units of 10

Filed Under: MCAT Video Transcriptions Tagged With: mcat video transcription

3 Month MCAT Plan

What does a 3-month MCAT Study Plan entail? Click to Read/Download

3 month mcat study plan leah4sci

Can I help you find a topic?

Download my Free Organic Chemistry Cheat Sheets by clicking on the image below



MCAT Tutorials, Videos & More

MCAT Home Page
Scroll down for orgo resources
MCAT Math Without a Calculator
MCAT Physics
MCAT Chemistry
MCAT Biology
MCAT Biochemistry
MCAT CARS / Critical Reading
MCAT Resources, Tips & More

Organic Chemistry Tutorials & Videos

Orgo Syllabus Companion
- Gen Chem Foundation for Orgo
- Orgo Basics Foundation
- Resonance Structures
- Naming Organic Compounds
- Acids and Bases
- Newman Projections
- Chair Conformations
- Chirality and Stereochemistry
- Fischer Projections
- Intro to Mechanisms
- Alkene Reactions
- Alkyne Reactions
- Free Radical Reactions
- Substitution Elimination Reactions
- Diels Alder
- Aromaticity & Electrophilic Aromatic Substitution (EAS)
- Alcohols
- Oxidation and Reduction
- Acetal / Ketal
- Enolate Reactions
- Proton NMR Spectroscopy

Organic Chemistry Study Guide Cheat Sheets

2025 MCAT Test Dates

Click image below for test + score release dates and more

Radicals: Reactions, Stability Hybridization+

Click for New Tutorial: All about Free Radicals

Free Radicals in Organic Chemistry - Hybridization, Stability, Resonance, Reactions and Mechanism Videos

MCAT Students Come Work With Me

Work with me to figure out exactly what YOU need to ace your MCAT

Option 1: Strategy, tutorials, my help every step of the way in the MCAT Study Hall
[click for details]

Option 2 One-on-one Private MCAT Tutoring

Orgo Students: Come Work With Me

Work with me to ace your Organic Chemistry Course
Option 1: Join me for bimonthly live review/Q & A Sessions, 50+ Hours of Topic-Specific review/practice sessions, direct access to me and so much more... [click for details]

Option 2 One-on-one Private Tutoring

Organic Chemistry Reference Material and Cheat Sheets

Alkene Reactions Overview Cheat Sheet – Organic Chemistry

The true key to successful mastery of alkene reactions lies in practice practice practice. However, … [Read More...]

Click for additional cheat sheets

MCAT Tutorials

mcat math without a calculator 1 play

Introduction To MCAT Math Without A Calculator

While the pre-2015 MCAT only tests you on science and verbal, you are still required to perform … [Read More...]

Click for additional MCAT tutorials

Organic Chemistry Tutorial Videos

KET Keto enol tautomerization reaction and mechanism leah4sci

Keto Enol Tautomerization Reaction and Mechanism

Keto Enol Tautomerization or KET, is an organic chemistry reaction in which ketone and enol … [Read More...]

Click for additional orgo tutorial videos

Copyright © 2025 · Leah4Sci - All Rights Reserved. · Sitemap · Log in