Unit+1+Real+Numbers+and+Properties

When you solve percents, such as, what is 50% of 2300... I like to put it as **x over 2300 equals 50 over 100.** You would then cross multiply the 2300 and 50, and then devide that by 100. By doing this you could find x, which is 50% of 2300.

_X_ = _50_ 2300 100 ---> 2300 * 50 = 115000. 115000 / 100 = 1150. Thus, 50% of 2300 is 1150.

This works for a lot of things, such as, if you had the information that 25% of a number is 224, what would be the number? You would set it up the same way, except now X would be on the bottom of 224, instead of the top. You could also find the percent, like if you had to find what is the percent of 40 of 520? You would put the X over the 100 and set it up the same way as before. :)

[|This] Really helped me with subjects i didnt know. It connects you to a tutor (for free) and they show you how to do a problem and give you help with a topic you dont understand. I didnt understand a subject and it really helped me. By:Katie [] This website shows how to add or subract real numbers. [] This website really helped me alot with my homework and understaning the topics.

Unit 1: Real Numbers and Properties Topic and/or Key Idea: Description  Here's a link to a video that explains the properties of the real numbers such as the closure, inverse, identity, associative, commutative, and distributive properties. Click >> [] ​ ​ and/or 100% || []
 * The associative and commutative properties: Did you know that many things in our daily lives also follow these properties? For example, "How many of you pour the cereal in the bowl first and then the milk? How about the milk and then the cereal?" This demonstrated the commutative property. When getting dressed in the morning, does it matter if you put on your pants and socks first and then your shirt? Or can you put on your shirt and pants on and then your socks? This is an example of the associative property. There are also examples that do not work to well, just like subtraction and division. (Remember 5 - 8 does not equal 8 - 5) For example, try putting on your socks and shoes in the reverse order. These examples will help you recall thes two properties.
 * Converting fractions to decimals: The following video describes how to convert between fractions and percents. It takes advantage of the definition of a percent, that being out of 100. media type="custom" key="4278613"
 * Visual representations of percents and fractions out of 100: The images shown here provide visuals of 3 different values. Did you notice that one of these values is less than 1 and the other 2 are greater than 1? I wonder what the picture would look like if the value was equal to 1. [[image:less_than_1.jpg width="257" height="161"]][[image:http://demonstrations.wolfram.com/PercentsAsFractionsOrDecimals/HTMLImages/index.en/popup_2.jpg width="225" height="156"]][[image:greater_than_2.jpg width="238" height="155"]]
 * Percent of a value: Find 30% of 80. [[file:% of a number 1.wav]] You want to leave a 15% tip on a bill of $40. How much tip should you leave?[[file:% of a number 2]] A pair of $80 sneakers is on sale for 20% off. What is the sales price?[[file:% of a number 3]]
 * Percent Change[[file:percent 9.16.09.bmp]] This image was adjusted by students in our class to show a 25% increase. These students added an additional 3 blocks to the picture. It looks like this now: [[file:percent 2 9.16.09.bmp]]
 * Fraction || Decimal || Percent ||
 * 1/9 || .111.... || 11.1% ||
 * 2/9 || .222.... || 22.2% ||
 * 3/9 || .333.... || 33.3% ||
 * 4/9 || .444.... || 44.4% ||
 * 5/9 || .555.... || 55.5% ||
 * 6/9 || .666.... || 66.6% ||
 * 7/9 || .777.... || 77.7% ||
 * 8/9 || .888.... || 88.8% ||
 * 9/9 and/or 1 || .999.... || 99.9%

The following website can help you to understand the associative, commutative, and distributive properties. The website provides good examples if you want a further understanding of those properties. []  Here are some basic examples for those three properties:

associative: (x + y) + z = x + (y + z)
 * It doesn't work with division and subtraction

commutative: c + a = a + c
 * It doesn't work with division and subtraction

distributive: x( y + z) = xy + xz

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this is a useful website. It's not as good as the one already posted, but it has links where you can practice converting numbers in scientific notation to standard notation and vice versa.