About this video
Sal adds 0.822 and 5.65 by writing them in columns with the decimal points lined up. He adds from the smallest place, treats the empty thousandths as 0, and regroups 14 tenths as 4 tenths and 1 one to get 6.472.
You'll be able to
- line up decimal points before adding.
- add starting from the smallest place value.
- regroup tenths into ones, like 14 tenths = 1 one and 4 tenths.
Key words
- decimal point
- The dot that separates the whole number part from the parts smaller than one.
- tenths
- The first place after the decimal point; 10 tenths make 1 whole.
- carrying
- Moving extra from one place to the next bigger place, like 10 tenths becoming 1 one.
Transcript
We're asked to add 0.822 to 5.65. So let me rewrite this. And when I rewrite it, I want to line up the decimals so that we add the right place to the right place. And so we could write either number first, although I like to write the larger number first. So let's write 5.65.
And remember, the important thing is that we line up the decimal points. So if we write 0.822-- so we line up the decimal. Let me line up the decimal first. So I'll write the decimal right below the other decimal. And it is 0.822. And now we are ready to add. So let's see what's going on here.
So I like to start in the smallest place. That way, the carrying works out well. So you might say, wait, I need to add this 2 thousandths to something. I don't see anything up here. Well, you could say there's just a 0 thousandths right up here. Then it makes it very clear.
Well, 0 thousandths plus 2 thousandths is going to be 2 thousandths. 5 hundredths plus 2 hundredths is 7 hundredths. 6 tenths plus 8 tenths is 14 tenths. Well, 14 tenths is the same thing as 4 tenths and 1 one. Another way of thinking about it is you're carrying the 1.
But really, what you're saying is, look, this is 14 tenths. I could write it as 4 tenths and a 1, or a ones place, a 1 in a ones place. Then you have 1 plus 5 is 6. And of course, you cannot forget the decimal. The decimal goes right there. And this is 6.472.
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