How to Round Decimals | Math with Mr. J

[Music] welcome to math with mr j [Music] in this video i'm going to cover how to round decimals now rounding is a very important skill because it's used all throughout math and life when we round we find a close or approximate value to the number we're working with rounding helps us make numbers easier and simpler to work with and can even make them shorter you've probably come across a very long decimal answer on a calculator or after working out a problem rounding decimals is very useful in these situations along with many others and again when we round we find a close value to our original number let's jump into our examples and see exactly how we round decimals so for number one we have six and seventy-eight hundredths the first thing that we need to do find the place that we're rounding to for number one we're going to round to the tenths place let's underline the digit in the tenths place so that's seven once we have that we look at the place and digit to the right so to the right of the tenths place we have the hundredths place in the hundredths place we have the digit eight so let's draw an arrow to show that we are looking to the right now that digit to the right is very important it determines if we round up or stay the same essentially what we're doing we're seeing is this closer to six and seven tenths or is it closer to six and eight tenths so five or more we round up four or less we stay the same well eight is more than five so we are going to round up i'm going to draw something that looks like an equal sign but it's with curved lines that means we're finding an approximate or rounded value so again we're rounding up so we are rounding to six and eight tenths that's our final rounded answer now i cut that decimal off after the tenths place when we round decimals we cut them off after the rounded place we don't need to change everything to the right to a zero like we do with whole numbers zeros to the right of a decimal do not change the value of that decimal so we can leave them off so again we can cut that decimal off after the rounded place so six and eight tenths our final rounded answer let's move on to number two where we have 455 thousandths let's round this number to the hundredths place underline the digit in the hundredths place so that five let's look to the right so we have a five in the place to the right so five or more we round up four or less we keep the digit the same well that's five or more so we round up so we round to 46 hundredths and we cut that off after the rounded place so after the hundredths place and our final rounded answer 46 hundredths now before starting number three i do want to mention that there are sayings to help you remember the rounding rules for example five or more raise the score four or less let it rest let's move on to number three where we have 27 and seven thousand three hundred ninety two ten thousandths let's round this one to the thousandths place so this nine right here look to the right we have a two so 5 or more or 4 or less well that's 4 or less so we keep that 9 the same here and our final rounded answer 27 and 739 thousandths moving on to number four we're going to round number four to the hundredths place so the six let's look to the right we have a three five or more or four or less well that's four or less so we stay the same and we round to 26 hundredths let's move on to number five where we have three and eight tenths so we're going to round this one to the ones place this is also known as rounding to the nearest whole number so we're seeing is this closer to three or is it closer to four let's look to the right and we have an eight so eight is five or more so we round up three and eight tenths rounds to four now if you were to put four decimal zero you change that tenths place to a zero this would still be correct these are equal but like we talked about earlier you can cut decimals off after the rounded place because zeros to the right of a decimal do not change the value lastly let's move on to number six where we have a very long decimal and we're going to round this one to the tenths place so let's underline the digit in the tenths this two look to the right we have a nine so is that five or more or four or less well nine is more than five so we round up so i will come below here so i have enough room this is going to round up to one and three tenths cut off after the tenths place right after the rounded place again final rounded answer one and three tenths so there you have it there's how you round decimals i hope that helped thanks so much for watching until next time peace you