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## 6th grade

# Adding three decimals

CCSS.Math:

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

## 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.