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Lesson 5: Visually add and subtract within 1,000

Learn to use regrouping, or carrying to add 709+996, 373+88, and 149+293. Created by Sal Khan.

## Want to join the conversation?

• What is "regrouping"? Is it the carrying of the 1s? Or is it the moving the 88 under the 373 as in the middle problem? I learned addition about 60 years ago, and the term "regrouping" wasn't used back then?
EDIT: I figured it out from the lesson on subtraction. It's both "carrying" and "borrowing". Thanks anyway! My mistake.
• Regrouping is carrying of the 1's in an addition problem, and borrowing of the 1's in a subtraction problem. So regrouping in addition and subtraction problems is the exchange of 10 ones for a ten (or the reverse exchange), 10 tens for a hundred (or the reverse exchange), 10 hundreds for a thousand (or the reverse exchange), and so on.

Have a blessed, wonderful day!
• why is the middle one horizontal at in the video?
• As Sal explain from onward, the reason it was initially horizontal, is to remind us, how we have to put the numbers vertically, with the ones aligned, and the tens aligned.
It's just a reminder that an addition might be presented in a test in this (horizontal) notation, and that we have to arrange them in the specific way to carry out the addition procedure.
• i don't know MaeleeT
(1 vote)
• how do you do this
(1 vote)
• what is 1 plus 1
(1 vote)
• 1 plus 1 is 2
(1 vote)
• 709 373 149 +996 88 +293
----- ------ ------
1,705 461 442

Don't question it
(1 vote)
• it was really easy