# why do we round numbers up and down

What is Rounding? Rounding means making a number simpler but keeping its value close to what it was. The result is less accurate, but easier to use. There are. Here we look at the

common method, the one used by most people. Decide which is the last digit to keep Leave it the same if the next digit is less than 5 (this is called rounding down But increase it by 1 if the next digit is 5 or more (this is called rounding up So: when the first digit removed is 5 or more, increase the last digit remaining by 1. Why does 5 go up? 5 is in the middle. so we could go up or down. But we need a method that everyone agrees to. So think about sport: we should have the same number of players on each team, right? And that is the common method of rounding. Read about. A farmer counted 87 cows in the field, but when he rounded them up he had 90. First work out which number will be left when we finish. Rounding to tenths means to leave one number after the decimal point. Rounding to hundredths means to leave two numbers after the decimal point. etc.

We may want to round to tens, hundreds, etc, In this case we replace the removed digits with zero. To round to so many significant digits, count digits from left to right, and then round off from there. When there are leading zeros (such as 0. 006), don\’t count them because they are only there to show how small the number is: (Try increasing or decreasing the number of significant digits. Also try numbers with lots of zeros in front of them like 0. 00314, 0. 0000314 etc) We were walking through the Wonderopolis the other day when we overheard an interesting conversation between a couple of Wolf 1: Hey Wayne! What are you doing with those? Wolf 2: Howdy Wendell! I\’m in the. 176Б177Б178Б Wolf 1: Cool! That would make me sleepy. Why are you counting them, though? Wolf 2: I invited all of them to a birthday party and I need to know how many pieces of cake I\’ll need. 181Б182Б183Б Wolf 1: Really?

Whose birthday party is it? Wolf 2: It\’s my party! 186Б187Б188Б Wolf 1: ButБhow did you get to come to a \’s party? Wolf 2: I wore my sweater when I invited them! 191Б192! I\’ll round up to 200 so I\’ll be sure to have enough cake. We something was up, so we went to find the to make sure he knew about the wolf\’s party. The wolves\’ conversation got us to thinking about rounding numbers, though. Why exactly do we do that? If you\’ve taken math classes for very long, then you\’ve probably learned how to round numbers. The most of rounding numbers goes as follows: first, decide which will be the last you keep (also known as the you\’re rounding to). Then, look at the next and leave the last the same if the next is less than five (round down) or the last by one if the next is five or more (round up). Finally, you the digits after the last with zero (or leave them off if rounding a decimal). Let\’s look at Wendell the Wolf\’s example to make it.

He counted 192 sheep and he decided to round to the nearest hundred. So 1 was in the hundreds place and that\’s the last that will be kept. The next was 9, which is more than 5. So Wendell rounded up by adding 1 to the 1 and replacing the other digits with zeros to get 200. What if Wendell had decided to round to the nearest ten? He counted 192 sheep, so 9 was in the tens place and that\’s the last that will be kept. The next was 2, which is less than 5. So Wendell would\’ve rounded down by keeping the last the same and replacing the with 0 to get 190. Rounding numbers makes them and to use. Although they\’re slightly less accurate, their values are still close to what they originally were. People round numbers in many different situations, including many real-world situations you\’ll find yourself in on a regular basis. For example, when you\’re calculating sales tax on a purchase you\’re planning to make, you may get a result such as $1. 7894. Since change is only handled in hundredths, you\’ll need to round up to $1. 79.

Likewise, you may need an easy way to make simple calculations in your head to determine how many bags of candy you\’re able to buy at the store. If you have $7 and bags of candy are $1. 79, then you know you can purchase 3 bags of candy. How do you know that? Without doing exact calculations, you can round the price of a bag of candy to $2 (rounding up is your safest bet, since it takes sales tax into consideration and gives you an estimate on the high side) and quickly determine that 3 bags of candy would be about $6 and 4 bags would be about $8. Finally, it\’s often just to work with rounded numbers, because exact numbers aren\’t only required. If it takes about 25 minutes to get somewhere, it\’s simply to allow yourself 30 minutes of travel time. If you\’re talking about the population of New York City, it\’s to work with a figure of 8 million people rather than a more exact figure of 8,214,426 people.