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Adding three decimals

Sal adds 7.056+605.7+5.67 using the "standard algorithm". Created by Sal Khan and Monterey Institute for Technology and Education.

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  • female robot amelia style avatar for user Hailey Franklin
    what is bigger 5.30 or 5.1000
    (119 votes)
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  • starky ultimate style avatar for user keshav2100
    How do you add negative decimals
    (8 votes)
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    • ohnoes default style avatar for user Linette Pan
      well, if you have say -0.5 + -1.5, you would think of it as a number line. SO our first number is -0.5, so we go -0.5 spaces to the left since left is negative on a number line. Then since you are adding another negative number, you go left 1.5 more spaces from tthe -0.5 you are already at, tto get -2.0, so basically add tthe numbers like they are two positive numbers then put the negative infront.
      Comment if you understand.
      (5 votes)
  • blobby green style avatar for user Cam R
    So i dont get how you do this could you please tell me?
    (7 votes)
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    • aqualine sapling style avatar for user fartface
      do a sheet of paper
      doing something like 15.80 + 8.20
      0 + 0 = 0
      8 + 2 = 10
      carry the 1
      5 + 8 + 1 = 14
      carry the one
      1 + 1 is 2
      combine those answers together
      you get 24.
      just so you know something like 5.20 + 4.60 is 9.80, so we do need the decimal point.
      (3 votes)
  • blobby green style avatar for user mireledaniel5
    so if i had to add 7.056 to 6098. what does that maank
    (4 votes)
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    • piceratops ultimate style avatar for user Hecretary Bird
      As with every addition problem, it becomes much easier if you just line up the places up correctly:
      6098.000
      + 7.056
      From here, we just add the places in order. From the thousandths place, we get a 6, since 0 + 6 = 6. For the next places:
      0 + 5 = 5
      0 + 0 = 0
      8 + 7 = 15, carry the 1 over to the next place
      1 + 9 + 0 = 10, carry the 1 over to the next place
      1 + 0 = 1
      6 + 0 = 6
      From this, we put all the separate problems together for the final answer. This is 6098 + 7.056 = 6105.056
      Hope this helped!
      (6 votes)
  • male robot donald style avatar for user William Forrester
    on adding decimals 4 does not make any sense plz help
    (4 votes)
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    • aqualine ultimate style avatar for user ChloeSpence
      Adding decimals is like adding normal numbers, with an addition of a decimal point.
      Say you have 1.054+3.002+7.514
      Take away the decimal points.
      1054
      + 3002
      + 7514
      Now, just add to get your over all number (this example's final total is 11570) Since you have this total, you need to add the decimal point.
      Find the number with the most amount of numbers behind the decimal, and make it so that 11570 has 3 numbers behind the decimal, which would be 11.570, or 11.57.
      (2 votes)
  • male robot hal style avatar for user Cameron Delong
    So 1.320000000000 is the same as 1.32
    (2 votes)
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  • male robot hal style avatar for user Xander Diaz
    Why is it that if a number goes before xero then you can put as many s you want but if it goes after you cant
    (3 votes)
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    • leafers ultimate style avatar for user Elly Na
      Alright.
      Does 9 and 09 and 000009 all have the same value? Yes.
      Does 9 and 90 and 900000 all have the same value? No.
      If it comes before a number, and also before the decimal, a zero makes no difference in the value of the number. If it comes after a number but before the decimal, though, it does.
      Hope this helps!
      (3 votes)
  • sneak peak green style avatar for user ¥€§ PL€4S€
    The numbers to the right of the decimal are technically considered negative numbers, right? And if so, how does it work compared to the negative numbers unit?
    (3 votes)
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  • primosaur sapling style avatar for user Saul
    why did sal put 605.7 longer then the rest of the numbers is it important or is that how you add three numbers
    thank you for answering
    (2 votes)
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  • blobby green style avatar for user lianmhf
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    (2 votes)
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Video transcript

We need to add 7.056 to 605.7 to 5.67. Now when you're adding any number, you always want to make sure you line up numbers in the same place. And especially when you're dealing with decimals, the easiest way to do that is to just line up the decimals. So let's do that. So the first number right here is 7.056. This second number right here is 605.7. And then this last number is 5.67. So now we have everything lined up. Everything that's in the ones place is below or above everything else in the ones place. Everything in the tenths place is below or above everything else in the tenths place, and so on and so forth. So we can add. So let's add it. So you want to start off in the smallest place. So you start off here. This is the tenths, hundredths, thousandths place. This is literally 6 thousandths, and you want to add it to the other thousandths. There aren't any other thousandths. So you can view it two ways. You can just bring in this 6 down, or you could view this 605.7 as the same thing as 605.700. You can add as many zeroes to the right of this decimal, to the right of the 7, as you want, since we're sitting on the right side of the decimal, without changing its value. You can also do it here. This 5.67, you can write it as 5.670. When you write it like this, and you have 6 plus 0 plus 0 is 6. And you keep going. 5 plus 0 plus 7 is 12. You write the 2 in the hundredths place, and carry the 1. 1 plus 0 plus 7 is 8, plus 6 is 14. Write the 4, regroup the 1 into the ones place. 1 plus 7 is 8. 8 plus 5 is 13. 13 plus 5 is 18. This is 18. Carry or regroup the 1. 1 plus 0 is just 1. And then finally. You have the 6 in the hundreds place. Nothing gets added to it, so you can just bring down that 6 and it's right there. And you don't want to forget the decimal. And so when you add the numbers you get 618.426, or 618 and 426 thousandths. And we're done.