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### Course: MAP Recommended Practice > Unit 33

Lesson 46: Common fractions and decimals# Common fractions (halves)

Lindsay discovers why 0.5 is equal to 1/2. Created by Lindsay Spears.

## Want to join the conversation?

- how do you do it with biger numbers like 75 or25? I understand how its done with 0.5/ 1/2, but with bigger nubers?(40 votes)
- oh whole numbers can not be simple fractions(17 votes)

- 5x2=10 that easier that way(22 votes)
- Okay, But like i- WHERE DID YOU GET THE 2? OR 5?(7 votes)

- how do you turn a fraction into a decimal(9 votes)
- how does 0.5=1/2 that makes no complete sense(8 votes)

- So, I got a question . 0.4 ? How can 0.40 add up to 1.00 if it doesn't have a multiple of 1.0?(12 votes)
- because the zero is nothing so its ok if we put it there(3 votes)

- what if its a big number like 100 and 200(11 votes)
- I kind of get it but not really but soon will(10 votes)
- how on earth does any of this make sense(10 votes)
- I really don't understand what to do! It's all really confusing...(9 votes)
- see what i mean please make a big number about common fractions(9 votes)
- I don't get how to turn 72 into a fraction(6 votes)

## Video transcript

- [Voiceover] Let's try to show that 0.5 is equal to one half. We often hear people use
these interchangeably. They use them back and forth. Maybe someone would say, I have a 2.5 pound rat and then someone would say back to them, wow, a two and a half
pound rat, that's enormous. If we get past thinking about
how enormous that rat is, what we can notice is they first said 2.5 and then they changed
it to two and a half. They use them interchangeably
because they're equal and that's fine. You can use these back and forth because they are equal to each other. .5 and one half are equivalent or equal but let's not just accept
that that's true, let's see, let's see if we can prove it. Let's try to show that. So the first way we can show it is down here with a number line. We have a number line
that goes from zero to one and it's divided into
one, two, three, four, five, six, seven, eight,
nine, 10 equal pieces so that means each of these pieces is one of the 10 equal
pieces or one tenth. So looking back at this decimal up here, this five is in the tenths place so we can also say 0.5 is five tenths is another way to read that decimal or we could say five tenths. So if this distance here is one tenth, if we travel another one,
we've gone two of the tenths, two of the 10 equal spaces. So to get to five tenths, we're going to travel
one, two, three, four, five of the tenths and right here, we have five tenths. We could write is as a fraction or we could write is as a decimal. So we found five tenths
on this number line but let's see if that really
is the same as one half. This distance here from zero to one, if we were to block that off, going to mark it off, this point right here
where we said five tenths, this distance, this whole
distance that we traveled is this much and we can see here that this is in fact half of the distance between zero and one. This is halfway. So 0.5 and one half are at the same point on a number line so that's one one to
show they're equivalent. Another way we can show that five tenths and one half are equal is with a fraction model. So here we have a rectangle and let's try to show one half. Let's start with one half this time. So if we split this rectangle in half, here we're trying to show half. One out of two equal pieces. So we'll shade one half, one of the two pieces. So this is one half and now, let's try to show that this
is equal to five tenths. Remember, this five is in tenths place. So now, instead of halves, we're going to divide our
rectangle into tenths, five tenths, so let's do that. Here we go. So we'll make 10 equal pieces for tenths and we will shade five of them. We want to see five of the tenths so let's do that. One, two, three, four and five. Here, we've shown five tenths and we can see that it
is equal to one half. One half and five tenths
cover the same amount so they are equal. So we've shown two ways now. One half and five tenths
were at the same spot on a number line which means they're equal and they cover the same amount of area which is another way
to show they're equal. So one half is definitely equal to 0.5 or five tenths.