To round numbers in math, determine whether the second digit in the number is more than five or less than five. Round up for numbers more than five and down for numbers four and fewer. Round numbers to the nearest 10, 100 or 1000 with help from a math teacher in this free video math lesson.
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So how does one round numbers? Hi, I'm Jimmy Chang, I've been teaching college math for 9 years and we're here to give you a few tips on how to round numbers. Now there's going to be a pattern involved and once you see the pattern, rounding becomes pretty straightforward after that. So here's a couple of quick examples for you. First we're going to talk about rounding to the nearest 10. Suppose you have let's just say the number 37. Now rounding to the nearest 10 that means it's either going to go round down to 30 or round up to 40. Now because we round to the nearest 10, your focus is going to be on the next digit over. So our focal point is on the number 7. Now a big rounding rule is if the number is 5 or more, you round up. But if it's less than 5, you round down. Now obviously because the 7 is 5 or more, that means that the 37 gets rounded to 40. Now here's another example. Suppose you have 149. You want to round to the nearest 100. It will either round up to 200 or round down to 100. Now because we round to the nearest 100, again you simply look at the next place over. Now because the digit is 4, it falls in the less than 5 category which says you must round down. So 149 rounds down to 100. And last but not least, suppose you have let's just say 3500, you want to round to the nearest thousand. That means the 3500 is either going to round up to 4000 or round down to 3000. Again, since you're rounding to the nearest 1000, look over at the next digit which is the 5. But as you can see, the 5 is part of the 5 or more criteria and if it's 5 or more you round up. So the 3500 rounds to 4000. So I'm Jimmy and this has been a glimpse on how to round numbers.