Sal shows some techniques for doing mental addition, such as making groups of 10 and 100. Watch the next lesson: https://www.khanacademy.org/math/cc-2nd-grade-math/cc-2nd-add-subtract-1000/cc-2nd-strategies-for-adding-two-and-three-digit-numbers/v/addition-using-groups-of-10-and-100?utm_source=YT&utm_medium=Desc&utm_campaign=2ndgrade Missed the previous lesson? https://www.khanacademy.org/math/cc-2nd-grade-math/cc-2nd-add-subtract-1000/cc-2nd-strategies-for-adding-two-and-three-digit-numbers/v/breaking-apart-three-digit-addition-problems?utm_source=YT&utm_medium=Desc&utm_campaign=2ndgrade 2nd grade on Khan Academy: Learn to see three-digit numbers as hundreds, tens, and ones About Khan Academy: Khan Academy is a nonprofit with a mission to provide a free, world-class education for anyone, anywhere. We believe learners of all ages should have unlimited access to free educational content they can master at their own pace. We use intelligent software, deep data analytics and intuitive user interfaces to help students and teachers around the world. Our resources cover preschool through early college education, including math, biology, chemistry, physics, economics, finance, history, grammar and more. We offer free personalized SAT test prep in partnership with the test developer, the College Board. Khan Academy has been translated into dozens of languages, and 100 million people use our platform worldwide every year. For more information, visit www.khanacademy.org, join us on Facebook or follow us on Twitter at @khanacademy. And remember, you can learn anything. ... https://www.youtube.com/watch?v=jAfJcgPGqgI Note: All Khan Academy content is available for free at (www.khanacademy.org)

87-91, pg. 163. Created by Sal Khan. Watch the next lesson: https://www.khanacademy.org/test-prep/gmat/problem-solving/v/gmat-math-17?utm_source=YT&utm_medium=Desc&utm_campaign=GMAT Missed the previous lesson? https://www.khanacademy.org/test-prep/gmat/problem-solving/v/gmat-math-15?utm_source=YT&utm_medium=Desc&utm_campaign=GMAT GMAT on Khan Academy: Sal works through the 249 problem solving questions in chapter 5 of the the 11th edition of the official GMAC GMAT Review (ISBN Number: 0-9765709-0-4 published in 2005) About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. ... https://www.youtube.com/watch?v=dA1u8RD49dU Note: All Khan Academy content is available for free at (www.khanacademy.org)