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Using place value to add 3-digit numbers: part 1

Learn to use regrouping, or carrying to add 536+398. Created by Sal Khan.

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  • blobby green style avatar for user Timothy Poisal
    I have discalcula. Is there anyway to simplify this? I feel embarrassed being 33 and totally lost when trying to solve this problem. I cannot add 8+6 in my head because I cannot see the numbers on my fingers. When you start to add "ten's and hundred's" into the equation, I am totally lost...
    (153 votes)
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  • piceratops seedling style avatar for user proud331
    How many different ways of addition can be used?
    (46 votes)
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  • aqualine tree style avatar for user Campbell
    Is there anything that some people do that can help me get addition facts down in my head? I feel like I don't have anyone to talk to about this because my parents are always helping my brother with his home work.
    (8 votes)
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    • piceratops ultimate style avatar for user EmmaB
      Write Notes that's the key to helping you organize information, don't write too much about the Concept to explain it just keep each Step short as possible but providing enough info telling you what to do then draw in some examples for you to look back at as you're learning, if you Color Coordinate write in to do that and why like... What you get confused by but again keep it short, just think about whether you NEED to make a Note of something or not if you can remember something without doing so, Carrying Numbers thou it's defo one to make note of.

      I suggest using Google Docs if you have a Google Account which you'll use with YouTube, go to the Google search engine page, click the icon with the 9 Dots at the Top/Right of the page and click Google Drive or Google Docs, they're both connected to each other so doesn't matter which you go but in Google Drive you can create Folders and organize Documents you create.

      I suggest creating a Folder for Maths then in that Folder right click in a blank area and click Google Docs and it will create a new Document for you. The rest is simple too you've got the Word Processor bit and the Toolbar above where you can select the Font, the Size, make Titles of each Concept Bold or change the Text Color. Or you could just write notes in a Lined Paper Pad but Google Docs you're not likely to lose any of your Notes and you can make copies.
      (0 votes)
  • starky tree style avatar for user Crystal Snake
    why can't we just add without regrouping?
    (5 votes)
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    • starky seed style avatar for user C
      It's all about place value. We need to keep the tens in the tens place, the hundreds in the hundreds place, and so on. If we added together without regrouping, ex: 15+15, we would get the wrong answer 210. We already used the tens place so we bumped it over, making 10+10 wrongly equal 200. We have to keep everything in its right column to get the right number instead of crazy huge ones. If we regroup the 1 in 10 to the left and then ADD ON THE REST OF THE TENS, we would get the correct answer 30.

      Good question. ^_^
      (2 votes)
  • piceratops seed style avatar for user nasir mcgeachy
    I need help with the adding 3 digit numbers
    (3 votes)
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    • blobby green style avatar for user sixtyforbitsarav
      Addition of 3-digit numbers
      Three-digit numbers sum is as simple as the sum of two-digit numbers and requires you only to learn with the sum of single-digit numbers and how to deal with carries.

      Steps to add 3-digit numbers:

      Step 1: Place the given 3- digit number below the another given 3-digit number and arrange them into columns according to their places like ones, tens, and hundreds.

      Step 2: Now start adding columns in a sequence starting from ones.

      Step 3: When the sum of two digits in once’s column is greater than 9 like 8 + 5 = 13, then put 3 in the result and pass 1 as a carry to the tens’s column which will add with numbers present in that column. This carry concept is the same for all the columns.
      (1 vote)
  • leaf orange style avatar for user Makayla Green
    is there 123,456,256,453
    (4 votes)
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  • blobby green style avatar for user rohan2444
    Can you please talk slower
    (4 votes)
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  • duskpin sapling style avatar for user 💜(Ak 47)Kitty cat lovers squd)💜
    whats going on?
    (4 votes)
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  • piceratops sapling style avatar for user Kenna
    I was just wondering why would we not just add the numbers like they are instead of carrying?
    (2 votes)
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  • aqualine tree style avatar for user yili10
    i do not know how to close the miove
    (4 votes)
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Video transcript

Let's add 536 to 398. I'm going to do it two different ways so that we really understand what this carrying is all about. So first we'll do it in the more traditional way. We start in the ones place. We say, well, what's 6 plus 8? Well, we know that 6 plus 8 is equal to 14. And so when we write it down here in the sum, we could say, well, look, the four is in the ones place, so it's equal to 4 plus one 10 So let's write that one 10 in the tens place. And now we focus on the tens place. We have 1 ten, plus 3 tens, plus 9 tens. So what's that going to get us? 1 plus 3 plus 9 is equal to 13. Now, we have to remind ourselves, this is 13 tens. This is 13 tens. Or another way of thinking about it, this is 3 tens. This is 3 tens and 100. You might say, wait, wait. How does that make sense? Remember, this is in the tens place. When we're adding a 1 ten plus the 3 tens plus 9 tens, we're actually adding 10 plus 30 plus 90, and we're getting 130. And so we're putting the 30. The 3 in the tens place represents the 30. So this is the 3. The 3 represents the 30. And then we're placing this 1 in the hundreds place. 10 tens is equal to 100. And now we're adding up the hundreds place. 1 plus 5 plus 3 is equal to-- let's see, 1 plus 5 is equal to 6, plus 3 is equal to 9. But we have to remind ourselves, this is 900. This is in the hundreds place. So this is actually 100-- I want to make all colors the same. So this is actually 100 plus 500 plus 300. Let me get the color coding right. Plus 300 is equal to 900. And that's exactly what we got here. 100 plus 500 plus 300 is equal to 900, and we're done. This is equal to 934.