https://www.khanacademy.org/math/cc-third-grade-math/imp-addition-and-subtraction/imp-strategies-for-adding-two-and-three-digit-numbers/v/addition-using-groups-of-10-and-100 2021-05-18T23:20:44Z Addition using groups of 10 and 100 Sal rewrites addition problems to make them easier to solve. video https://cdn.kastatic.org/googleusercontent/pbyapocY2vyhPgKLRv_1i5h3aTYmSYUvxJFah9IBOBxbaJrC_LdxMDp2HshH31LIaWHRcbw7BM1KTuLvgS7M_Tk Addition using groups of 10 and 100 Sal rewrites addition problems to make them easier to solve. https://cdn.kastatic.org/ka-youtube-converted/Nq88IHw4Y9E.mp4/Nq88IHw4Y9E.mp4 238 Adding by carrying over https://www.khanacademy.org/math/cc-third-grade-math/imp-addition-and-subtraction/imp-strategies-for-adding-two-and-three-digit-numbers/e/making-100-and-1000 2021-05-18T23:20:44Z Add using groups of 10 and 100 Practice making groups of 10 and 100 while adding 3-digit numbers.  Lindsay Spears exercise https://www.khanacademy.org/math/cc-third-grade-math/imp-addition-and-subtraction/imp-adding-with-regrouping-within-1000/v/example-adding-with-carrying 2021-07-07T20:19:26Z Adding 3-digit numbers Learn to use regrouping, or carrying to add 709+996, 373+88, and 149+293. Sal Khan video https://cdn.kastatic.org/googleusercontent/hgHcTsRKnLiu92VE5fvxzDn7XZKd7qcCjoYBO84ozDq0K8hGjQPFJoZ9_CfOBHip-hg5Hhw_4u7AB5kY5x7f7RoJ Adding 3-digit numbers Learn to use regrouping, or carrying to add 709+996, 373+88, and 149+293. https://cdn.kastatic.org/ka-youtube-converted/9hM32lsQ4aI.mp4/9hM32lsQ4aI.mp4 184 Adding by carrying over https://www.khanacademy.org/math/cc-third-grade-math/imp-addition-and-subtraction/imp-adding-with-regrouping-within-1000/e/addition_4 2021-04-29T07:53:38Z Add within 1000 Practice adding three-digit numbers. All sums are 1000 or less. Lukas Domagala exercise