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## Khan Academy

United States

Joined Nov 17, 2006

Khan Academy is a 501(c)(3) nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. Our interactive practice problems, articles, and videos help students succeed in math, biology, chemistry, physics, history, economics, finance, grammar, and many other topics.

Khan Academy provides teachers with data on how their students are doing so they can identify gaps in learning and provide tailored instruction. We also offer free personalized SAT and LSAT practice in partnership with the College Board and the Law School Admission Council.

Our resources have been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy each month.

Khan Academy provides teachers with data on how their students are doing so they can identify gaps in learning and provide tailored instruction. We also offer free personalized SAT and LSAT practice in partnership with the College Board and the Law School Admission Council.

Our resources have been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy each month.

# Video

**Course Mastery Sal (intro only)**

Views 11K4 days ago

**Mastery Learning in Mr. Vandenberg’s Class**

Views 6K5 days ago

**Introduction to the mole and Avogadro's number**

Views 8K14 days ago

**Introduction to average atomic mass**

Views 8K17 days ago

**Subtracting fractions with unlike denominators introduction**

Views 8K20 days ago

**Emperical formula from mass composition**

Views 1.9K21 day ago

**Adding fractions with unlike denominators introduction**

Views 6K21 day ago

**Fraction multiplication as scaling examples**

Views 5K27 days ago

**Estimating adding fractions with unlike denominators**

Views 2.2K27 days ago

**Coulomb's Law and trends in the periodic table**

Views 11KMonth ago

**Groups, valence electrons and ionic compounds**

Views 1.9KMonth ago

**Example using ionization energies to identify element**

Views 1.8KMonth ago

**Groups of the periodic table**

Views 3KMonth ago

**Introduction to photoelectron spectroscopy**

Views 802Month ago

**Aufbau principle for electron configuration**

Views 1.3KMonth ago

**Introduction to photoelectron spectroscopy**

Views 554Month ago

**Percent composition of mixtures**

Views 855Month ago

**Valence electrons**

Views 749Month ago

**Orbitals, shells and energy levels**

Views 9KMonth ago

**Introduction to electron configuration**

Views 4.2KMonth ago

**Worked example Percent composition of a mixture**

Views 3.4KMonth ago

**Percent composition of mixtures**

Views 1.6KMonth ago

**Empirical formula from combustion reaction**

Views 756Month ago

**Example comparing mass percentages of element in comounds**

Views 496Month ago

**Equivalent fractions on number lines**

Views 4KMonth ago

**Comparing fractions word problems**

Views 799Month ago

**Equivalent fractions with models**

Views 4.6KMonth ago

**Subtracting mixed numbers with regrouping**

Views 968Month ago

**Adding mixed numbers with like denominators**

Views 398Month ago

**Mixed number addition with regrouping**

Views 1.1KMonth ago

**Mixed number subtraction**

Views 1.2KMonth ago

**Fraction multiplcation on the number line**

Views 567Month ago

**Multiplying mixed numbers**

Views 885Month ago

**Reform in the Gilded Age | AP US History | Khan Academy**

Views 6KMonth ago

**Area models for factoring expressions**

Views 4.4K2 months ago

**Multiplying expressions with area models**

Views 1.7K2 months ago

**Interpreting features of a quadratic model**

Views 1.2K2 months ago

**Worked examples factoring completely**

Views 1.3K2 months ago

**Exponential decay word problems**

Views 7182 months ago

**Analyzing mistakes when finding extrema example 2 | AP Calculus AB | Khan Academy**

Views 2.8K2 months ago

**Geometric series convergence and divergence examples | Precalculus | Khan Academy**

Views 2.6K2 months ago

**What to think about when taking over an existing business?**

Views 6K2 months ago

**How do you know if a business idea is worth pursuing?**

Views 3.4K2 months ago

**How to handle naysayers when starting a business?**

Views 2.6K2 months ago

**What advice do you have for someone wanting to be an entrepreneur?**

Views 3.9K2 months ago

**How do you prepare yourself mentally to be an entrepreneur?**

Views 3.9K2 months ago

**Fundamental theorem to evaluate derivative**

Views 1.4K2 months ago

**Introducing Khan Academy Learnstorm 2019!**

Views 17K2 months ago

**Harmonic series and 𝑝-series | AP®︎ Calculus BC | Khan Academy**

Views 5K2 months ago

**Time past between two clock faces**

Views 9402 months ago

**Finding the end time for a movie in 24 hour time | Math | Khan Academy**

Views 4802 months ago

**Length of a trip in 24 hour time | Math | Khan Academy**

Views 3752 months ago

**The rise of industrial capitalism | AP US History | Khan Academy**

Views 5K2 months ago

**Celebrate 10 years of Khan Academy! 🎂**

Views 55K2 months ago

**Fractions in context**

Views 2.6K2 months ago

**Relating fractions to 1**

Views 1.2K2 months ago

**Finding 1 on the number line**

Views 5082 months ago

**Fractions greater than 1 on the number line**

Views 6362 months ago

**Writing whole numbers as fractions**

Views 6982 months ago

**Comparing unit fractions**

Views 6512 months ago

**Relating number lines to fraction bars**

Views 6682 months ago

**Graphing logarithmic functions (example 2) | Algebra 2 | Khan Academy**

Views 1.5K2 months ago

**Graphing logarithmic functions (example 1) | Algebra 2 | Khan Academy**

Views 8082 months ago

**Dividing polynomials by x (no remainders) | Algebra 2 | Khan Academy**

Views 7K2 months ago

**Multiplying monomials | Polynomial arithmetic | Algebra 2 | Khan Academy**

Views 2.2K2 months ago

**Graphing square and cube root functions | Algebra 2 | Khan academy**

Views 8102 months ago

**Scaling functions introduction | Transformations of functions | Algebra 2 | Khan Academy**

Views 4.1K2 months ago

**Solving equations by graphing: word problems | Algebra 2 | Khan Academy**

Views 3252 months ago

**Solving equations by graphing: graphing calculator | Algebra 2 | Khan Academy**

Views 2322 months ago

**Approximating solutions with graphing calculator**

Views 7322 months ago

**Extraneous solutions | Equations | Algebra 2 | Khan Academy**

Views 8222 months ago

**Solving equations by graphing: intro | Algebra 2 | Khan Academy**

Views 2622 months ago

**When and why extraneous solution happen**

Views 1.9K2 months ago

**Zeros of polynomials (multiplicity) | Polynomial graphs | Algebra 2 | Khan Academy**

Views 7932 months ago

**Finding inverses of rational functions | Equations | Algebra 2 | Khan Academy**

Views 7402 months ago

**Rational equations intro | Algebra 2 | Khan Academy**

Views 6422 months ago

**Quadratic systems: a line and a parabola | Equations | Algebra 2 | Khan Academy**

Views 4252 months ago

**Solving equations by graphing | Algebra 2 | Khan academy**

Views 2602 months ago

**Multiplicity of zeros of polynomials | Polynomial graphs | Algebra 2 | Khan Academy**

Views 9012 months ago

**Zeros of polynomials: plotting zeros | Polynomial graphs | Algebra 2 | Khan Academy**

Views 3382 months ago

**LearnStorm Classroom Celebrations**

Views 12K3 months ago

**Polynomial division introduction | Algebra 2 | Khan Academy**

Views 2.1K3 months ago

**Zeros of polynomials introduction | Polynomial graphs | Algebra 2 | Khan Academy**

Views 7893 months ago

david pierce2 hours agoThe current educational model is at least two centuries behind the times. The size of a room that holds thirty students allows an instructor to be heard without having to shout. Other than that there is no particular advantage to restricting a group to thirty students. Although technology has changed, the current educational model has not. The internet (RU-clip in particular) allows an instructor to reach millions of students at a time and do a much better job transferring knowledge. If a concept is not clear the lecture can be viewed over and over until it is completely understood. This is not possible with the traditional outdated educational system. A more complete understanding of the subject matter takes time, study and practice, yet all too often course material is just memorized, tested and then forgotten due to time constraints that cannot be avoided in a traditional classroom setting. david

90's Kid2 hours ago"Tower of Babel". Learn this story from the Bible. You'll get your answer.

Sofie Won2 hours agook watching this in 2019 and I have a question-- so how is the protein processed and "matured" when mRNA attaches itself to a free-floating ribosome instead of one that's attached to an E.R.?

Vikashrohit Sharma2 hours agoThis is wrong channel for learn english. Don't teach us error education. Box>boxes not boxen. I am not lol.🤣🤣🤣🤣🤣

Ravenstrike7212 hours agoI thought I was confused before this video. I now know I had no idea what confused really was, until now.

KingLegend763 hours agoArgued this with my friend today and he kept saying I was wrong when I was saying continuous is where it is like an irrational number, they can have no ending, no precise number, or infinite values within two numbers, I knew I was right

Jonathon Tordilla3 hours agoThank you Mr. Khan! I've learned so much from Khan Academy, and your lessons allowed me to accelerate my learning by two years! I placed out of Precalculus, Calculus 1, Calculus 2, Chemistry, and Physics, and most of my success is because of your educational videos. I now truly believe that I can learn anything, and I'm determined to make a difference in the world. I hope that some day I can adequately repay you.

brooke3 hours agoeric out here saving my sat score

Evil Devil3 hours agoIt's very easy to understand, very nice!

Winnie Chan4 hours agothe question is in grams or kilograms?

Teresa Flores4 hours agoThank you so much..... Very well explained!!!!!!! Thank you again

Obligatory Fail4 hours agoWatching a 240p video on a 1440@144 monitor, it's crazy how fast the technology has improved over the last ten years.

Samuel Amidu Kamara5 hours agoWell understood

Nikki Aho5 hours agoOMG I LOVE KHAN ACADEMY THERE ONLINE SCHOOLS AMAZING. They are so good at explaining and helping.

Sonagi5 hours agothis has to be the worst explanation yet.

Jack Mead6 hours agoI like to think of it as "The combined effort of both vectors". Khan Academy is a blessing!

Yesha Dalope6 hours agoI’m gonna fail my midterm exam! I still can’t get it! Am I too slow to not understand how to solve it?

Elizabeth Glasby6 hours agoim bored

Jam Ace6 hours agoTrying to learn hours worth of lessons here right before the exams

Valerie Crespo6 hours agoWhat if you have to solve for no real solutions with [i]

Jazmin M6 hours agoyou didn't finish teaching the first way before you got carried away into another way.. way too confusing

AJ Morrison6 hours agoHow does this guy write so neat with his mouse lol

prathamesh datar7 hours agoCompleted the entire series. Loved it!

Moaz El-sawaf7 hours agoThanks a lot sir <3

Grey Ham8 hours agoim so confused ap world is taking a toll

sanjeev yadav8 hours agotax from $10 to $1 KHAN FOR PRESIDENT

applebug8 hours agoThe dreaded stats course :/ WHYYY :/ So difficult for me to retain.

PHOTON8 hours agoi can never understand the whole projection stuff...Like how does that help me? I see the projection, but how does this relate to the topic?

MiddleEastMixTapes9 hours agoThis has to be the most useless thing to learn

Sarah Griffin9 hours agoThank you so much. This helped me with my homework that I was stressing out about because I didn’t understand. But now I do

Ian Petrus Tan9 hours agoat 3:06, khan only took the positive square root of cos y, implicitly rejecting the negative root of cos y. why did he do that?

Jayla Cowan9 hours agoyou have to do b'h divided by two and b'h so he is wrong

David Brown9 hours agoHolly cow! I didn't know this!

Just Because9 hours agoCan you raise your voice just a little bit please

إبتسام احمد9 hours agoIslam means peace not surrender Muslim means one who submits to god

elmotasembella shwekat9 hours agoyour boring.

Angelicom10 hours ago*please be my math teacher*

Courtney McLean10 hours agothe mouse eats the coyote

Thuli Ncube10 hours agoThank you so much for this simple and understandable tutorial.

jmasik10011 hours agoTypical mechanical explanation. But there is no application as to why. I just need to know the significance of the Standard Error of the sample mean. It's easy to get the figures...but why is the Standard Error necessary?

Esha Moha11 hours agoi feel that i forget everything since i had 1 year break so i gotta start from the beginning i hope it works out for me

Jerry Xue11 hours agoi don get this

Md Shajid11 hours agoanyone from bangladesh?

Saurabh Pimpalkar11 hours agoSo u mean to say there were no hindu kings ruling in india hmmmm.... See people how they are disorting our history. No Rajput, No maratha, No peshwa.. no cherro, No Sikhs, just only muslims... Waah

Fuseteam11 hours agowelp now i feel old

György Márk11 hours agothis kinda explanations really makes me excited about math :)

erolxtreme11 hours ago51% of Hugo to stop there, EVEN IF he will not find the card he was searching for.

AJ Paulson11 hours agoI’m a sixth grader

Gurnoor Aulakh11 hours agoE N D O P L A S M I C R E T I CU L U M

Christina Cao12 hours ago8:20 for polyploidy

Audio Stories12 hours agoI still don't understand🤦🏽♀️

Behrouz Javid12 hours agoYou had a mistake in the minute 4:30. g(6)=23.2 not 20.

Kairy Barazi, M.D.12 hours agoHi a don’t like math my dad made me watch this

Kairy Barazi, M.D.12 hours agoI don’t really like math but I like this ✅ thank you

maggie La12 hours agoYou are GOD

Veronica Leigh Johnson13 hours agoMy question is do the use of male pronouns prohibit women from becoming President? Can the wording be used by Republicans to challenge the first woman president we get?

wethepeople197013 hours agoRARITY

kainat khan13 hours agoI didn't get the hydrogen bonding part.. if some one can explain please do it

Euston Chinhara13 hours agohow did you draw the graph you lied there

Diana Rogava13 hours agoI never understood why water was split into oxygen and hydrogen! Now I do! thank you very much

Kevin Ingraham13 hours agothis was white people just trying to keep blacks enslaved it's such a pity to think some still are

moment ous13 hours agoMost absurd thing ever. Self interest does not lead to good for all atleast in respect to most businesses and corporations these days

Maria Khan13 hours agoThat wasn't complex :( I was searching for more complex ones they give in high school exams here in India

Forklift1713 hours ago8:56 should be "and", not "or"

Coco_gacha14 hours agoThank you You help meh with a quize I have trmorrow 🙂

Lamborghini Aventador14 hours agoI meant to type the game sentence

GioIn144p14 hours agogeez this video helped so much thanks!!

I am Beautiful Nora14 hours agoWhy did u put minus before a second matrix???

mujeebzahir15 hours agoru-clip.com/video/mrU1fnrhajs/video.html

speed master15 hours agoMy teacher said watch khan academy s videos he is an amazing person

Capitalist Gentleman15 hours agoThank you for being correct. Anarcho-capitalism is the true right.

Sem S15 hours agomy guy took 6 minutes to say 's/n'

Dương Dương16 hours agoThis is a way to be a good math teacher: ru-clip.com/video/TaRoOJKutE8/video.html

l h17 hours agoTo learn some things you need a certain level of I.Q and if you don't have that level then you can't learn your way there.

Al7ammadi17 hours agoThank you now I can stude for my SWQ for 9th Grade

Andrea Duran17 hours agoI get this and wrote notes and everything but my equation is 5x^2+10x+6 and I got stuck. Can someone explain to me please

A Montenegro17 hours agoI love khan academy! 😍

Jimmy Arce18 hours agoThank you Sal for doing your best at giving access to education to everyone at every place and time as it should be!!! Much respect!! (:

upendra kumar18 hours agoThis is worst video

Adam H718 hours agoComputational Mathematics has me permanently glued to this channel

America Lost18 hours agoThe Republican Party is the party of cowards and hypocrites who couldn't care less about the country and its Constitution as long as they get reelected. SHAME!

J K Lee19 hours agoWhy couldn't he just pick squirrels instead of rabbits if his Freudian slip keeps calling out squirrels?

Rodrigo Marinho19 hours agoI took a different approach. Since sqrt(c) is not an integer, and is the sum of two other Square roots, then sqrt (c) = z.sqrt(k), sqrt (b) = y.sqrt(k) and sqrt (a) = x.sqrt(k), thus z = x + y. Let's say b is the smaller, so a = 60 + b. But b = y².k, so a = 60 + y²k = x²k. x²k - y²k = 60 k(x+y)(x-y) = 60 Sum and difference must be both odd or even. For the 1st case, k = 4, which is a perfect square and goes against the fact that it can't. So k = 3, 5 or 15. k = 3 has x = 6 and y = 4 k = 5 has x = 4 and y = 2 k = 15 has x = 2 and y = 0 So a is Max when x = 6, and k = 3, which gives us 108. Therefore b = 48. 108+48=156

Arsema H19 hours agoThis is the best .It really helps to understand its concept and is easy to understand. for those of you who haven't seen it yet check it out.

tony duvall19 hours agoYou sir are best teacher I've ever hard. Thank you.

nirmal saha19 hours agoBut , where is PIE language?

ItsUr Mom19 hours agoPleass donate for khanacademy

danish Ali19 hours agoHindi me samjaeo

Wade Brink19 hours agothanks for helping me i was scared to ask much teacher you a life saver Khans academy :)

Ayan Dalal20 hours agoWhat the heck is the lady doing on the side of the screen.

It'sCurryAndRice PlusWater20 hours agoI'm watching this and my midterm exam is tomorrow

Elena Olivare21 hour agoI think i can understand you more than my teacher in math

Sniber shot21 hour agoanyone from 2019

Henry Collins21 hour agoWhat about inflation, bank charges, tax?

Tatyanns21 hour agoFructose carbonyl is in the middle vs Glucose is on the end

Stella Galenzoga21 hour agoThankss

Izaan Shaikh21 hour agoI wish you replace my school teacher

Colin Latham21 hour agoEBITDA can sometimes be used to distract investors from the lack of real profitability. EBITDA in the 1980s was used as a tool to assist with leveraged buyout investors examined distressed companies that needed financial restructuring. They used EBITDA to calculate quickly whether these companies could pay back the interest on these financed deals. in the 1980s to measure a company's ability to service the debt used in a leveraged buyout (LBO). During the "dot com" bubble when companies had very expensive assets and debt loads that were obscuring what analysts and managers felt were legitimate growth numbers. In conclusion EBITDA does not fall under generally accepted accounting principles (GAAP) as a measure of financial performance. Because EBITDA is a "non-GAAP" measure, its calculation can vary from one company to the next. Note: EBITDA does not fall under GAAP generally accepted accounting principles .

Leena Chauhan22 hours agoThis video helped me on my home work

Sakeena Zehra Gulzar22 hours agoKHAN ACADEMY, KEEP IT UP!!! THE BEST LEARNING CHANNEL. I REALLY LOVE IT FROM BOTTOM OF MY HEART! EXCELLENT job!