How to Add Decimals | Math with Mr. J

[Music] welcome to math with mr j [Music] in this video i'm going to cover how to add decimals now if you're able to add whole numbers you're going to be able to add decimals just a couple of different things as far as setting up the problems go if you get how to set up the problems you're going to be good to go let's jump into our examples and start with number one where we have eighteen and four tenths plus six and seventy two hundredths so when we set these problems up we wanna make sure that we line our decimals up that's going to line up all of our places so number one we're going to do eighteen and four tenths plus six and seventy two hundredths notice how the decimals are lined up now it may look a little offset there but we can use placeholder zeros to better align this and make it look a little more organized meaning eighteen and four-tenths we can put a zero in the hundredths place that way we look a little more lined up remember zeros to the right of a decimal do not change the value that's an equivalent decimal so we are able to do that we're not changing the value of the problem once we have that we add start with the hundredths place so zero plus two is two then we move to the tenths place four plus seven is eleven so put our one and regroup or carry there now bring our decimal straight down it's lined up throughout the entire problem now we add the ones 1 plus 8 is 9 plus 6 is 15. regroup or carry the one now we add the tens place one plus one is two so we get twenty five and twelve hundredths to recap as far as where we put the decimal in our answer the decimal should be lined up throughout the entire problem so we bring it straight down now before i move on to number two i do want to mention a common mistake and that's going to be lining the digits up meaning for number one it would look like this 18 and four tenths plus six and seventy two hundredths so three digits lined up with three digits so you can see that the decimals are not lined up therefore our places are not lined up and we're not going to place the decimal correctly in our answer so this is going to give us something completely incorrect and is a common mistake so avoid just lining the digits up make sure you have the decimals lined up now it is possible that you line the decimals up and then the digits line up as well most important part being the decimals are lined up let's try another example and move on to number two where we have 55 and 909 thousandths plus 23 and 3 tenths so first step line up our decimals so 55 and 909 thousandths plus 23 and three-tenths so we can use placeholder zeros to line this up a little better so we can place some zeros to the right of 23 and three-tenths remember zeros to the right of a decimal do not change the value that's an equivalent decimal so we can do that our last step we add so nine plus zero is nine zero plus zero zero nine plus three is twelve regroup or carry the one our decimal comes straight down then we add the ones one plus five is six plus three is nine and then we end with the tens so five plus two is seven so our final answer 79 and 209 thousandths so there you have it there's how you add decimals i hope that helped thanks so much for watching until next time peace