Rounding to Whole NumbersDate: 04/01/2001 at 23:10:19 From: Leslie Subject: Rounding whole numbers Hi, Do you know how to round to the nearest whole number? I don't have a clue. Date: 04/02/2001 at 08:38:03 From: Doctor Peterson Subject: Re: Rounding whole numbers Hi, Leslie. We have a discussion of this in our Dr. Math FAQ on the topic, though it focuses on decimals: http://mathforum.org/dr.math/faq/faq.rounding.html The idea is that you want to find the whole number nearest to a given number. Suppose that number is 3.4. If we put it on a number line, it will look like this: 0 1 2 3 4 5 +---------+---------+---------+---------+---------+ ^ It is between two whole numbers, 3 and 4. Which is closer? You can tell by looking that 3 is closer to 3.4 than 4 is, so the nearest whole number is 3. Is there any quicker way to tell? Well, if the number had been 3.5, it would be exactly halfway between 3 and 4; since .4 is less than .5, we know that the lower number, 3, is closer. So the rule is, look at the tenths place (the first digit you will be dropping to change the number to a whole number), and see whether it is more or less than 5. If it's less than 5, you "round down" to the lower whole number; if it's 5 or more, you "round up" to the higher number. If the number you are given is EXACTLY halfway between (like 3.5), then there is no nearest whole number, and we just have to choose a rule to go by. The usual rule (in schools) is to follow the rule I gave above, and round 3.5 up to 4. In more advanced math, other rules are sometimes followed in this case, but you don't need to worry about that yet. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/ |
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