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Lesson 3: Divide decimals by whole numbers

# Dividing a decimal by a whole number with fraction models

The video explores the concept of dividing decimals by whole numbers. It emphasizes visualizing the process, using the idea of converting tenths to hundredths to make division more intuitive.

## Want to join the conversation?

• i needed to explain to my sister that 0.4 s the same as 0.40 and then she was like, "But 40 is bigger than 4!"

That's 30 minutes I will never get back again.
• Have your sister draw a circle, and cut it into 10 pieces, and then shade in 4 slices.
Then have her draw a circle with 100 slices, and shade in 40 slices.
Then ask her which one is bigger or if they are equal in size.
She might then understand then that .4 = 4/10 and .40= 40/100
• Would we be able to do it this way?

0.4= 4/10
5=5/1
and then divide normaly?
• Yes, you can.
(4 / 10) / (5 / 1) = (4 / 10) * (1 / 5) = (4 / 50) = 0.08
• Who else dose this for school?
• yes i did
(1 vote)
• Does anyone else find this a little confusing? Because how do you know that the "8" is supposed to be in the hundreths??
• so 8 times 5 = 40 and in this instance the
the 4 in the forty is in the tens place
the 0 is in the ones place.
The 8 and 5 are in the ones place.
sooooo
0.40 is like 40 all over again.
The 4 is in the tenths place
The zero is in the hundreths place

S0 the 8 and the 5 are in the hundreths place.
(1 vote)
• Doing the Long Division I get a quotient of 12.5...
Can anyone explain?
• Why can’t you do it this way?

0.4*10 = 4
5*10 = 50
4/50 = 1/(50/4)
1/(50/4) = 1/12.5
1/12.5 = 8/100
8/100 = 0.08
• we are brothers
(1 vote)
• If you just change the number to the bigger place value, would you just put the fraction in decimal form?
(1 vote)
• He needs to explain it a bit more better than he's explaining it now.
(1 vote)
• this is very helpful thank you
(1 vote)
• Why is the final answer in that video 0.08? It doesn't make any sense to me...
(1 vote)
• 40÷5 equals 8. Because we are talking about hundredths, it's 0.08
(1 vote)

## Video transcript

- [Instructor] In this video, we're going to try to figure out what 4/10 divided by five is. So pause this video and see if you can think about it before we work through it together. We're really going to think about approaching this visually. All right, now let's work through this together. Let's actually try to think about what 4/10 looks like. So if you view this entire square as a whole, you see that we've divided it into 10 equal columns or 10 equal sections, and four of those tenths are shaded in, so what you see here in blue is 4/10. But how do we divide that into five and make sense of it? Well, one way to think about it is to imagine 4/10 not just as 4/10, but to imagine it as 40/100, so this would be imagining it as 40/100. So we can re-write 4/10 divided by 5 as 40/100 divided by 5, and now we can think about taking these 40 hundredths, each of these little squares is a hundredth, and divide it into five equal sections, and then we can say, well, how many hundredths are in each of those five equal sections? So let's do that. So let's see, this is one, this is two, this is three, this is four and then we have five equal sections. So how many hundredths are in each of those equal sections? Well we can see in each of them you have one, two, three, four, five, six, seven, eight. So 40/100 divided by five is going to be 8/100, because we have eight of these little squares in each of those five equal sections. So 8/100 we would like this. And so 40/100 divided by five is 8/100, then 4/10 divided by five is also equal to 8/100.