About this video
Sal subtracts 9.57 - 8.09 by lining up the decimal points. Because 7 hundredths is less than 9 hundredths, he regroups one tenth into 10 hundredths, then subtracts each place to get 1.48.
You'll be able to
- line up decimal points before subtracting.
- regroup one tenth as 10 hundredths when I need more hundredths.
- subtract decimals to the hundredths place.
Key words
- regroup
- Trade one unit in a place for 10 units in the next smaller place.
- hundredths
- The second place after the decimal point; 0.01 is one hundredth.
- tenths
- The first place after the decimal point; one tenth equals 10 hundredths.
Transcript
Let's try to subtract 9.57 minus 8.09. So try to pause this video and figure this out first before we work through it together. All right. Well, let's just rewrite it. Let's rewrite it. And when I rewrite it, I like to line up the decimals. This one it's a little intuitive.
We have 8.09. Just like that, and now we're ready to subtract. And we want to subtract 9 hundredths from 7 hundredths. Well, we don't have enough hundredths up here so let's move over here. Let's see if we can do some regrouping so we always have a higher number on top.
So over here we want to subtract 0 tenths from 5 tenths so we have enough tenths over here. So let's regroup. So instead of 5 tenths, I'm going to have 4 tenths, and then I'm going to give that other tenth, which is the same thing as 10 hundredths over here, so this becomes 17 hundredths.
17 minus 9 is 8. 4 minus 0 is 4. And then I have 9 minus 8 is 1. So this is going to be 1.48.
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