5th grade (Eureka Math/EngageNY)
- Estimating decimal division
- Estimating with dividing decimals
- Dividing decimals
- Division strategies for decimal quotients
- Multi-digit division strategies for decimals
- Divide whole numbers with decimal quotients: 78÷12
- Divide whole numbers to get a decimal (2-digit divisors)
- Pattern when dividing by tenths and hundredths
- Divide whole numbers by 0.1 or 0.01
Sal uses understanding of place value, expanded form, and fractions to help divide with decimals.
Want to join the conversation?
- Wouldn't the answer to .63 divided by .07 be .09 or would it just be 9 and why?(10 votes)
- A really simple way to find out is to multiply the quotient (.09) by the divisor (.07). If your answer is correct, the product will be equal to the dividend (.63). As you can see,
.09 x .07 = .0063, so that can’t be right. But 9 x .07 = .63, which makes sense, because if you have 63 hundredths and you divide them into groups of 7 hundredths, you will have 9 groups.(10 votes)
- I don’t get how you move the decimal 2 to the right. How do you do that?(5 votes)
- Basically, moving the decimal 2 places to the right is moving the decimal to a different location in the number. For example, 72.85. I want to move the decimal 2 places to the right so that I can divide it by 9.05. We need to do this for both numbers. And so, after moving the decimals, becomes the whole number s"7,285" divided by "905". Now we can divide.
So basically :
72.85 -----> 728.5 ------> 7,285. We just moved the decimal 2 places to the right.(5 votes)
- At2:35Sal says that you can turn your improper fraction into a mixed number. What happens if your improper fraction is equal to a whole number(4 votes)
- What if i have something like 7.8 / 30? Im still not sure how to do that?(4 votes)
- 1) 30 can't go into 7.8 so your answer will have a whole number of 0.
2) 30 goes into 78 2 times. So, your answer is now up to 0.2
3) Multiply and subtract: 2(30) = 60. 78-60=18. Add a 0 to get 180 and divide again.
4) 30 goes into 180 6 times. So the answer is now at: 0.26
5) Multiply and subtract: 6(30)=180. 180-180=0. There's no remainder, so we're done.
Answer: 7.8 / 30 = 0.26
Hope this helps.(2 votes)
- i keep struggling with division and decimals and this was not helpful. what should i use?(2 votes)
- but if you make a decimal problem into a decimal to to make it easier, how does it make the problem easier? I still don't get it.(3 votes)
- [Instructor] In a previous video we started thinking about strategies for dividing numbers where either the numbers are decimals, or their quotients are going to be decimals. So now let's continue that, and we're gonna do a slightly more involved examples. So let's say we wanna figure out what 500 divided by 200 is. Divided by 200. Pause this video and see if you can figure that out. Well, one strategy for doing this is to just re-express this as a fraction and see if you can simplify this fraction in a way that it's straightforward to express it as a decimal. So for example, this is going to be the same thing. This is equal to 500, 500 over 200. And now we can simplify this. We can say this is the same thing as five times 100, five times 100, over two times 100. The reason why that is useful is you say, "Hey look, I have a hundred in the numerator, "I have a hundred in the denominator, "a hundred divided by a hundred is just going to be one." So, you could just do this. This is equal to five halves. Five halves times. Times 100 over 100. Times 100 over 100. Which is just going to be equal to, which is just going to be equal to one. Another way to think about it, you could divide the numerator by a hundred. And you would have five, and as long as you divide the denominator by the same thing, you're not changing the value of the fraction. So if you divide the denominator by a hundred, you're going to get two. So, any way you think about it, this could be simplified as five halves. But we're not done yet. That is what 500 divided by 200 is. But can we express this as a decimal? Well we can rewrite five halves as a mixed number. So five halves is going to be equal to, well how many times does two go into five? Well it goes two times, and then you have one half left over. So this is going to be two and one half. And now how do we express this right over here as a decimal? Well, you might recognize that one half is the same thing as five tenths. So this is going to be equal to two and five over ten, which of course we can write as 2.5, or two and five tenths. So 500 divided by 200 is 2.5. Let's do another example. Let's say we wanted to figure out what 0.63 divided by 0.07 is. Pause this video and see if you can come up with a strategy for doing this. Well there's multiple ways to tackle it. One way is to think about both of them in terms of hundredths. So for example, this is 63 hundredths. And this right over here is seven hundredths. And so if you have 63 of something, and you're dividing that by seven hundredths, what are you going to get? Well, you're going to, if you took your seven hundredths, and you multiply it by nine, you're going to get 63 hundredths. And so 63 of something divided by seven of that same something is going to be equal to nine. This is going to be equal to nine. Seven times nine is 63. So seven hundredths times nine is going to be 63 hundredths. Another way to think about it is we can express this as a fraction. So in the numerator, you have 0.63 and in the denominator, you have 0.07. And if the decimals are bothering us, we can multiply both the numerator and the denominator by the same value to get rid of the decimals. So let's multiply the numerator by 100, and also multiply the denominator by 100. This doesn't change the value of the expression because multiplying by 100 over 100 is just the same thing as multiplying by one. So this would be equal to 63 hundredths times 100. Well we would move the decimal two to the right. This is going to be equal to 63 over seven hundredths times 100. Once again we move the decimal two to the right. This is going to be seven. So 63 divided by seven, once again, that is going to be equal to nine.