Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/arithmetic/addition-subtraction/sub_borrowing/e/subtraction_4?utm_source=YT&utm_medium=Desc&utm_campaign=Arithmetic Watch the next lesson: https://www.khanacademy.org/math/arithmetic/multiplication-division/mult-div-concept/v/multiplication-intro?utm_source=YT&utm_medium=Desc&utm_campaign=Arithmetic Missed the previous lesson? https://www.khanacademy.org/math/arithmetic/addition-subtraction/sub_borrowing/v/alternate-mental-subtraction-method?utm_source=YT&utm_medium=Desc&utm_campaign=Arithmetic Arithmetic on Khan Academy: So you're ready to have some arithmetic fun? You've come to the right spot! It's the first "official" math topic and chalked full of fun exercises and great videos which help you start your journey towards math mastery. We'll cover the big ones: addition, subtraction, multiplication, and division, of course. But we don't stop there. We'll get into negative numbers, absolute value, decimals, and fractions, too. Learning math should be fun, and we plan on having some with you. Ready to get started? 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=OJ-wajo6oa4 Note: All Khan Academy content is available for free at (www.khanacademy.org)

Sal subtracts 31 from 64 by thinking about tens and ones. Watch the next lesson: https://www.khanacademy.org/math/cc-2nd-grade-math/cc-2nd-add-subtract-100/cc-2nd-sub-two-dig-intro/v/regrouping-to-subtract-one-digit-number?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-100/cc-2nd-sub-two-dig-intro/v/subtracting-2-digit-numbers-without-regrouping?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=RzEFGpe0rv4 Note: All Khan Academy content is available for free at (www.khanacademy.org)