Adding decimals: science experiment
About this video
Mia pours 0.9 liter of vinegar and 0.3 liter of oil into a container. The video adds 0.9 + 0.3 by lining up the decimal points: 9 tenths plus 3 tenths is 12 tenths, which is 1 whole and 2 tenths, so there is 1.2 liters in total.
You'll be able to
- add decimals in tenths by lining up the decimal points.
- explain that 12 tenths is the same as 1 whole and 2 tenths (1.2).
- solve a word problem by adding decimal amounts.
Key words
- tenths
- Parts of a whole split into 10 equal pieces; 0.3 means 3 tenths.
- liter
- A unit for measuring how much liquid there is.
- regroup
- Trade 10 of one place for 1 of the next bigger place, like 10 tenths for 1 whole.
- decimal point
- The dot that separates the wholes from the parts of a whole.
Transcript
- [Instructor] We're told, "Mia is doing a science experiment. She pours 0.9 liter of vinegar into a container. Then, she adds 0.3 of a liter of oil to the container. How much total liquid is in Mia's container?" Pause this video and try to figure that out. All right, so what we really want to do is we want to add 0.9 liters to 0.3 liters.
So let's just do that. So we are going to have 0.9, and I could put the units there if I like, and I'm going to add that to 0.3. Now when I'm going to add things, I want to make sure that my decimals are lined up so I can add the same places to the same places.
So let's get started. So we can go to the tenths place. I have 0.9 plus 0.3. That's 12 tenths. Now I can't write 12 tenths in the tenths place, but I could write that 12 tenths is the same thing as 0.2 and a whole. Or another way to think about it, it's the same thing as 1.2, if you have 0.9 plus 0.3.
Or another way, sometimes people would say, "Write the 2. Carry the 1. Regroup the 1." But the reason why you're doing that, this is 12 tenths, and 12 tenths is the same thing as 0.2 and a whole. And then I have 1 whole and no other wholes, so it's just going to be 1 whole right over there, and then my decimals right over there, and I am done.
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