Dividing Decimals Explained: A Step-By-Step Review | Understanding Decimal Division

[Music] welcome to math with mr j [Music] in this video i'm going to go through a quick review of dividing decimals this should be helpful for anyone looking for a quick refresher whether you're in middle school high school college continuing your education as an adult really no matter what class or goal you are working towards here are a couple of examples to get this down let's jump into number one where we have 85 and eight tenths divided by six now the first thing that we're going to do we're going to set the problem up and place our decimal for number one we have 85 and 8 tenths for our dividend that's the number we are dividing so it goes under our division bar so let's write out 85 and eight tenths and then we are dividing by our divisor of six so the divisor is the number we are dividing by once we get to this point and we are set up we have a very important question is our divisor a whole number if yes our decimal goes straight up into our answer for number one our divisor is whole we have a six so let's bring that decimal straight up into our answer so our decimal is placed and we are ready to move on now i do want to mention for number two we will see what happens when we do not have a whole number for our divisor so once we bring that decimal straight up into our answer we can divide as we normally would with whole numbers so we're going to use the same division process that we use with whole numbers divide multiply subtract bring down repeat so let's start with divide so we have 8 divided by 6. how many whole groups of six are in eight well one then we multiply one times six is six subtract eight minus six is two and then we bring down now we repeat so divide 25 divided by 6. how many whole groups of 6 in 25 well 4. multiply 4 times 6 24 subtract we get 1 and then bring down our 8. so we repeat now we go back to divide eighteen divided by six how many whole groups of six in eighteen three multiply three times six is eighteen subtract we get a nice clean cut zero there and we are done we went all the way over to our furthest place value to the right in the case of number one that's going to be the tenths place and then we get that clean cut zero so we don't have anything left over we do not need to continue the problem now for number two we'll see what happens once we go all the way over and we do not get that zero there at the bottom once we subtract but for number one we are done our final answer 14 and three-tenths let's move on to number two where we have three and ninety-four hundredths divided by four tenths so we need to set this up three and ninety-four hundredths is our dividend the number we are dividing and we are dividing by four-tenths so once we're set up we need to see if our divisor is whole well 4 10 is not a whole number so we cannot bring the decimal straight up quite yet if our divisor is not whole we need to make it whole making the divisor a whole number gives us the ability to go through our division steps and it's going to place our decimal for us in our answer it's pretty cool how this works out in order to make our divisor whole we need to move the decimal once to the right which means we are multiplying it by 10. so let's move this decimal once to the right now in order to keep this problem balanced whatever we do to the outside the divisor we must do to the inside the dividend again this keeps the problem balanced and equivalent let's move the decimal once on the inside as well so multiplying the dividend by 10 also once we get to this point we need to rewrite the problem with the whole divisor and the decimal placed so we have 4 for our divisor and then 39 and 4 10 for our dividend now is our divisor whole yes so we can bring our decimal straight up now it's placed where we need to have it in our answer and we can go through our division process now we start with divide so we have 3 divided by 4. how many whole groups of 4 are in 3 well we can't do that so we need to move over and use that 9 as well and work with 39 so we have 39 divided by 4. how many whole groups of 4 are in 39 well 9 that gets us to 36. so let's write this 9 above the 39 there not above the 3 make sure it goes above the 39 the 9 and 39 because we used both of those digits for our divide step now we multiply so 9 times 4 36 subtract we get 3 then we bring down and repeat so we have 34 divided by 4. how many whole groups of 4 in 34 well 8 that gets us to 32. so eight times four thirty-two subtract we have two now we went all the way over to the furthest place to the right but we do not have a zero at the end there once we subtract it we do not want to put nine and eight tenths remainder two we want to keep this in decimal form for the whole problem so what we need to do we need to work until we get a clean cut 0 there at the end and that's going to be our completed problem so we need to put something on the end of this decimal to bring down and continue our process so what can we put on the end of our decimal that will not change the value of that decimal well a zero remember zeros to the right of a decimal do not change the value of that decimal so we can use a zero here and bring that down in order to continue our process so we brought down the zero now we repeat we go back up to divide so we have 20 divided by four how many whole groups of four are in 20 well five that hits 20 exactly and we can extend that bar there now we multiply 5 times 4 is 20. and now we have that clean cut 0. we went all the way over we needed to use a placeholder 0 in order to continue our process which is perfectly fine and then we worked to get that clean cut 0 and our final answer in decimal form and that is going to be 9 and 85 hundredths so there you have it there's a quick review of dividing decimals i hope that helped thanks so much for watching until next time peace