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Dividing decimals with hundredths example 3

Video transcript
Welcome to the presentation on dividing decimals. Let's get started with a problem. If I were to say how many times does 0.28 go into 23.828? So you're going to see that these dividing decimal problems are actually just like the level 4 division problems. You just have to figure out where to put the decimal. So what you do is you always want to take this decimal and move it over as many spaces as necessary to turn this number into a whole number. So in this case, we have to move it one space, two spaces over to put the decimal here. Well, if I did that with this number I have to do it with this number as well. So I moved it over two spaces to the right, so I have to move this decimal two spaces to the right-- 1, 2. Decimal goes here, and I put the decimal right above, right there. Now I can treat this 28 as a whole number. And if I want to, let me see if I could-- well, I want to erase the old decimal because if you were doing it with a pen you would kind of have the same problem I have. So now we do it just like a level 4 division problem. So we say, how many times does 28 go into 2? Well, no times. 2 is smaller than 28. How many times does 28 go into 23? Once again, still, it goes into it zero times because 23 is smaller than 28. How Many. Times does 28 go into 238? So let's think about that. 28 is almost 30. 238 is almost 240. So 30 goes into 240 eight times Because 3 goes into 24 eight times. So I'm going to guess that 28 goes into 238 eight times. And it literally it a guess. You have to try out some numbers sometimes. 8 times 8 is 64. 8 times 2 is 16. Plus 2 is 22. Subtract. I get 14. I guessed right because the remainder when I divide 28 into 238 and I say it goes into it eight times is 14, which is less than 28. So 8 was the largest number of times that the 28 could go into 238 without being larger. So now I bring down this 2. Once again, you recognize this is just purely a level 2 division problem-- a level 4 division problem. So now I say, how many times does 28 go into 142? Well, once again, I'm going to approximate. 28, it's almost 30. Let's see, 30 times 4 is 120. So yeah, I'll take a guess and I'll say let's say it goes into it four times. I could be wrong, but let's see if it works out. Let me get rid of this old 6. 4 times 8 is 32. And 4 times 2 is 8. Plus 3 is 11. 2 minus 2 is 0. 4 minus 1 is 3. Huh. Interesting. So it turns out that my remainder here is larger than 28, so I actually could have divided 28 into 142 one more time. So let me go back and change that. See, it's not a mechanical thing. And if you feel unsure sometimes, you just have to try numbers and see if they work. And otherwise, you raise or lower the number accordingly. So let me erase that 4. I'm going to try not to mess up. Erase all this stuff down here. I probably should have tried it out on the side first before doing all this and I wouldn't have had to go back and erase it. And then let me get back to what I was doing. So when I went into it four times the remainder was too large, so let me try five now. 5 times 8 is 40. 5 times 2 is 10. Plus 4 is 14. 142 minus 140 is 2. Good. 2 is less than 28. This 5 is correct. Now I just bring down the 8. 28 goes into 28 exactly one time. 1 times 28 is 28. Remainder of 0. Done. So 28 goes into 2,382.8 85.1 times. Or you could say, 0.28 goes into 23.828 85.1 times. That's the answer we had gotten. And that makes sense. It's always good to do a reality check because if I took 85.1 and I multiplied it by 0.28, it makes sense that I'd get a number around 23. 0.28 is almost 1/3. So 23 is almost 1/3 of 85. So at least it makes sense in rough numbers. When you're doing decimals, if I had gotten 800 here instead of 85, I'd be like, oh, well, 0.28 times 800? I don't know if that equals 23. So it's always good to just do a reality check and get a sense for at least the magnitude of what your answer should be. Let's do another problem. Let's do 3.3 goes into 43.23. That's a 3. So first thing we want to do is move the decimal. We just have to move it one space here, so we move it once space here as well. Put the decimal right up here. And now it's just a level 4 division problem. 33 goes into 4 zero times. 33 goes into 43 one time. That's easy. 1 times 33 is 33. Do the subtraction. 43 minus 33 is 10. Bring down this 2. 33 goes into 102? You could eyeball that one and say, about three times because 3 times 33 is 99. 3 times 33 is 99. 102 minus 99? Well, that's easy. That's 3. We just bring down this 3. 33 goes into 33 one time. 1 times 33 is 33. 0. So 3.3 goes into 43.23 13.1 times. Or, if you move the decimal over, and when you move the decimal over to the right one spot, all you're doing is you're multiplying both the divisor and the dividend by 10. Which is fine as long as you multiply both of them by 10. It's also like saying 33 goes into 432.3 13.1 times. Let's do one more problem. I think I have time. YouTube puts a limit on this stuff. so let's say 2.5 goes into 0.3350 how many times? Well once again, let's move the decimal point over one here. So we move the decimal point over one here. Put the decimal here. So how many times does 25 go into 3? Well 0. So you could put a 0 here just for fun if you want. How many times does 25 go into 33? Well, it goes into it one time. 1 times 25 is 25. 33 minus 25 is 8. Bring down the five. 25 goes into 85? Well, we know 25 times 3 is 75. So it'll go into it three times. 3 times 25. We know that's 75. 85 minus 75 is 10. Bring down the 0. Up here we had brought down the 5 before. And 25 goes into 100 four times. So our answer is 2.5 goes into 0.3350 0.134 times. So as you see, the only difference step between what we're doing when we're dividing decimals and when we're doing level 4 division is we just have to make sure we get the decimal in the right place. You shift the decimal here enough so that this becomes a whole number and you just have to shift the decimal here the same number of times. And once you do that it just becomes a level 4 division problem. And the whole trick with level 4 division is always be willing to try numbers, and if the numbers don't work, adjust them accordingly. Don't feel that there should be a way that you can just always power through these problems. You have to do a little bit of trial and error and maybe use your eraser or do some work on side every now and then. But anyway, I think you're ready to do some dividing decimals problems. I hope you have some fun.