How to Divide a Decimal by a Whole Number | Math with Mr. J

[Music] Welcome to Math with Mr. J. In this video, I'm going to cover how to divide decimals by whole numbers. Let's jump into number one where we have 73 and 8/10 / 3. The first thing that we need to do is set this problem up. That way we can go through the division process. 73 and 8/10 is the dividend, the number we are dividing. So it goes under the division bar. 73 and 8/10 / 3. Three is the divisor. The number we are dividing by. It goes on the outside of the division bar. Now whenever we have a division problem that involves decimals, we always need to check is the divisor a whole number. If yes, bring the decimal straight up into the answer. So for number one, our divisor is three. That's a whole number. So we bring the decimal straight up into the answer. Now we go through the division process. The same process we use when we divide whole numbers. So divide, multiply, subtract, bring down, repeat. We start with divide. So we have seven divided by three. How many whole groups of three in seven? Well, two. That gets us to six. Now we multiply. 2 * 3 is six. Subtract. 7 - 6 is 1. And then we bring down. Now we have 13. And we repeat. So we go back to divide. 13 / 3. How many whole groups of three in 13? 4. That gets us to 12. Now we multiply. 4 * 3 = 12. Subtract 13 - 12 is 1. And then we bring down the eight. Now we have 18. And we repeat. So we go back to divide. 18 / 3. So how many whole groups of three in 18? 6. That equals 18. Exactly. Multiply. 6 * 3 18 subtract and we get zero. So we went all the way over to the furthest place to the right which was the 10th's place for number one and we have a cleancut zero here. That tells us that we are done. Our final answer 24 and 6/10. For number two, we will see what happens when we do not get that cleancut zero and we need to extend the problem until we do. Let's move on to number two where we have 46 and 62 hundreds / 15. Let's start by setting this problem up. 46 and 62 hundreds divided by 15. Is the divisor a whole number? Yes, 15 is a whole number. That means we bring the decimal straight up into the answer. And now we go through the division process. So we start with divide. We have four divided by 15. How many whole groups of 15 and four? Well, we can't do that. So, we need to use the six as well. And take a look at 46. We have 46 / 15. How many whole groups of 15 in 46? Well, three. That gets us to 45. Make sure that 3 goes above the six in 46, not above the four. Since we used both of those digits and we had 46 / 15, that 3 needs to go above the 6. Now we multiply 3 * 15 is 45. Subtract 46 - 45 is 1 and then bring down. Now we have 16 and we repeat. So back to divide 16 / 15. How many whole groups of 15 in 16? 1. Now we multiply 1 * 15 is 15. Subtract 16 minus 15 is 1. Bring down the two. And now we have 12. So repeat. And we go back to divide. 12 / 15. How many whole groups of 15 in 12? Well, we can't do that. So we need a zero here. And now we multiply. 0 * 15 is 0. Subtract. 12 minus 0 is 12. So, we went all the way over to the furthest place to the right, the hundredth's place. But we have a 12 at the end. We do not have a cleancut zero yet. That 12 does not mean remainder 12 like when we work with whole numbers. This answer is in decimal form. So, we need to keep it that way. What we need to do is extend the problem until we do get a cleancut zero. And that will mean the problem is done and we have our final answer. We can do this by using placeholder zeros that we can bring down. So let's use a placeholder zero in the thousandth's place that we can bring down and continue this problem in order to work towards that final answer. Now remember zeros to the right of a decimal do not change the value of that decimal of that number. So we are able to use this strategy. Let's bring this zero down and continue the problem. So now we have 120 and we repeat. So we go back to divide. We have 120 / 15. How many whole groups of 15 in 120? Well 8. And that hits 120 exactly. Now we multiply 8 * 15 is 120. Subtract 120 - 120 is 0. So now we have that cleancut zero and we are done with this problem. We have our final answer 3 and 108,000. So there's how we divide decimals by whole numbers. Let's move on to a couple of practice problems that you can try on your own. Here are your practice problems. I'll give you four minutes and then we will go over the answers. Go ahead and start. [Music] [Music] [Music] Heat. Hey, Heat. [Music] Heat. Heat. Hey, hey, hey. [Music] Hello. [Music] [Music] [Music] [Music] Hey, hey, hey. Okay. Okay, so that was 4 minutes. Let's go over the answers. So here are our answers. For number one, we have 32 and 9/10 / 7. That equals 4 and 7/10. For number two, we have 65 and 5200s / 12. That equals 5 and 46 hundredths. So there you have it. There's how to divide decimals by whole numbers. I hope that helped. Thanks so much for watching. Until next time, peace.