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### Course: 4th grade>Unit 10

Lesson 1: Decimal fractions

# Writing a number as a fraction and decimal

Sal shows the connection between decimals and fractions using a grid diagram and number lines.

## Want to join the conversation?

• any tips when my 10 yo daughter keeps writing 1/2 as 0.12 instead of 0.5? She is usually a quick learner but is struggling with simple fractions
(54 votes)
• Well,@Adele Canny, you could teach your daughter to remember by conceiving that 1/2 means 0.5 as 2 slashes 1 and cuts it in half and thus leaving 0.5 in each side and when these two join up, they make a 1. 1/4 4 slices 1 into 4 parts and they are 0.25 and when the combine the make 1

If your daughter is a quick learner then I suggest that she should what sal khans videos again and again until she catches on.
(37 votes)
• What if the blue dot is before 1/10 and after zero what’s the answer
(17 votes)
• you would have to make it into 100ths. If it were before 1/100 and zero you would add a zero to make it 1000ths and so on.
(9 votes)
• How do you make 1,999/2,000 a decimal?
(16 votes)
• Umm… I'm not so sure. But I think it’s, 0.1999
(4 votes)
• What is .76 as a fraction
(11 votes)
• It is 76/100
(10 votes)
• Why each hashmark represent a hundred?
(9 votes)
• Each hash mark represents a hundredth (1/100) on this line, just because that's the way it is. You can figure this out because there's 10 evenly spaced hash marks from 0 to 1/10, so to get the increment of each hash mark, you divide 1/10 by 10, getting a length of 1/100 for each hash mark.
It's only 1/100 for this number line. You can make number lines with whatever scale you want to, to best help you solve the problem.
(15 votes)
• Express the location of the point on the number line was confusing. Why counting by hundredths? What video can I see to review this concept further?
(14 votes)
• well for example 0.2 the 2 at the end is 10ths soo...
0.20 is 100ths and so on and on
(2 votes)
• my question why do decimals end up with zero somtimes
(14 votes)
• How can I make 16/24 as a decimal
(8 votes)
• 0.66666666666... and goes on forever
(9 votes)
• How are decimals related to fractions?
(3 votes)
• Fractions are decimals... let me explain!
Here's a fraction: 1/10.
1/10 as a decimal is 0.1.
Whenever you have a fraction smaller than a whole number it is a decimal such as: 1/7, 7/8, 5/6, etc. I think you get that.
Fractions such as: 1/1, 7/7, 10/10, etc., are whole numbers.
Fractions such as: 7/5, 2/1, 8/4, etc., are mixed fractions. A mixed fraction is a fraction that is a whole number and a decimal. For example, 5/2 equals 2.5, we have two whole numbers and 0.5 as our decimal.
Let me know if this helped you out a little bit with understanding how a decimal is related to a fraction. I hope I helped you out!! 😁👍✌️
(5 votes)
• Can someone help I didn't get it at 1 min 35 sec
(4 votes)

## Video transcript

- [Voiceover] We are told the square below represents one whole. So this big square here represents a whole. Express the shaded area as both a fraction and a decimal. So let's see, we've taken the whole and we've divided it into one, two, three, four, five, six, seven, eight, nine, ten, equal sections. Each of these columns or each of these tall rectangles represent one tenth of the whole because they are ten equal sections that it has been split into. So each of these is a tenth and let's see we have filled in one, two, three, four, five, six, of those tenths. So if I wanted to represent it as a fraction I would say this is 6/10 and if I were to represent it as a decimal I would say, okay, well, I have zero ones and I have six tenths, so as a decimal it is 0.6. Let's do a couple more of these examples. So let's say, so okay, look at that. Now I have, let's see, the big square represents one whole. Express the shaded area as both a fraction and a decimal. So what's going on over here? So I have ten rows and in each row I have ten squares. So ten times ten. This has a hundred squares in it. So I've divided my whole into a hundred equal sections. So each of these little squares is one hundredth. So here I have shaded in one, two, three, four, five out of the hundred hundredths, or I could say I have five hundredths right over here. So as a fraction, I could write this as 5/100 and as a decimal I could say, oh, I have no ones. I have no tenths and I have five hundredths. Let's do a couple more examples of this. So let's say that I wanted to... Let's see, it says, express the location of the point on the number line as both a fraction and a decimal. All right. So let's think about it. So this is 2/10, this is 3/10. And you see it is 0/10, 1/10, or this is 0, 1/10, 2/10, 3/10, and before each, or between each tenth they've split it into ten equal sections. One, two, three, four, five, six, seven, eight, nine, ten. So each of these, each of these little hashmarks represent one hundredth. So one way you could view this is we're at two tenths, so we have two tenths, and then we're going to have one, two, three, four, five, six, seven hundredths. So we could view this point as two tenths and seven hundredths. So actually let me write it as a decimal first. So we have two tenths and we have seven hundredths. Now another way to think about this is we have 27 hundredth. You can count them. Remember each of these is one hundredth. So zero, one, two, three, four, five, six, seven, eight, nine, ten, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 27 hundredths. And most people when they see this number they won't say two tenths and seven hundredths. They'll just say 27 hundredths. Well how do you write 27 hundredths as a fraction? Well, it's 27/100. 27 over, over 100. Let's do, I don't know, I'm kind of in the mood. Let's do one more of these. The big square represents one whole. Express the shaded area as both a fraction and a decimal. So we've already seen, there's a hundred of these. The whole is split into a hundred equal, smaller sections. So each of these small squares is a hundredth and so how many hundredths do we have shaded in? So this is going to be ten hundredths, 20 hundredths, 21 hundredths. So as a fraction I'd write that as 21/100. Now, you could, there's a couple of ways to think about it. If we're familiar with it already we would say okay, look, two tenths is the same thing as 20 hundredths, so it's going to be two tenths and one hundredth, or 21 hundredth. Another way to think about it is this first row right over here, that's a tenth, then this next one is a tenth, so you have two tenths, and then you have a hundredth over here. So any way you want to think about it. This is 21 hundredths or two tenths and one hundredth.