Multiplying Decimals Explained: A Step-By-Step Review | Understanding Decimal Multiplication

[Music] welcome to math with mr j [Music] in this video i'm going to go through a quick review of multiplying 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 six and seven tenths times four now the first thing that we're going to do when we have a multiplication problem that involves decimals we're going to remove any decimals within the problem so we're going to multiply just like we would if we had whole numbers let's set this up and rewrite number 1 as 67 times 4 so again remove any decimals we're going to worry about placing the decimal in our answer once we multiply so once we remove the decimals we can multiply so we'll start with 4 times 7 which is 28 so carry that 2 and then we have 4 times 6 which is 24 plus that 2 is 26. now we're done multiplying so we can place our decimal in our answer so we take a look at the original problem and see how many digits are behind or are to the right of a decimal well one we have this seven right here to the right of a decimal so our answer is going to have one digit to the right or behind the decimal so one digit would be this eight so we can place our decimal in between the six and the eight our final answer 26 and eight tenths let's move on to number two where we have five and twenty one hundredths times three and eight tenths so let's remove the decimals and rewrite this problem so 521 times 38. now we're ready to multiply so 8 times 1 is 8. 8 times 2 is sixteen put our six carry the one and then eight times five is forty plus that one is forty one so we are done with the eight and we are done with this carried one so we're going to move over to the three we're moving one place value to the left so we need our placeholder zero here and now we multiply starting with three times one which is three three times two is six and then three times five is fifteen now we add so eight plus zero is eight six plus three is nine one plus six is seven four plus five is nine and then we have a one so once we get to this point we look at our original problem and see how many digits are to the right or are behind a decimal well this 2 would be 1 this one would be 2 and then this 8 would be 3. so we have 1 2 3 digits behind or to the right of a decimal so our answer needs 3 digits to the right of the decimal so we have 1 two three digits our decimal is going to go between the nine and the seven our final answer 19 and 798 thousandths so there you have it there's a quick review of multiplying decimals remove the decimals multiply as you normally would with whole numbers and then place your decimal in the answer look at the original problem see how many digits are to the right or are behind a decimal and then your answer is going to match that i hope that helped thanks so much for watching until next time peace