There is really only one way to convert decimals to fractions, and I think that is the way that most people use. The way I do it is to first just read the decimal in my head. Then you can just write that in fraction form. For example, lets say you have the fraction .9; you would read this as nine tenths. When you read that, it is pretty obvious that the fraction is 9/10. You can do this with any decimal no matter how long it is.
Here's another example of converting decimals to fractions: the decimal is .1329. How would you convert that? Well all you have to do is read it: one thousand three hundred twenty-nine ten-thousandths. It is kind of long and confusing, but still easy to understand that the fraction is 1329/10,000. Whenever you add another place to the decimal, you add a zero to the denominator of the fraction. That is how you convert decimals to fractions.
There are a few different ways to convert a fraction to a decimal, but there are two very common ones that I think of first. First there is the method where you just divide it, and then there is the method where you have to make the denominator one hundred, so it can be a percent in the hundredths place. When I am converting fractions to decimals, my favorite method is to just divide the numerator by the denominator. So if you had a fraction such as 1/4 all you do is divide 1 by 4 and get .25 as the answer. In my opinion, that is the easiest way to do it, and is how I do it every time. There is another way too, but I think it is more complicated and time consuming.
The other way to convert a fraction to a decimal is to make a ratio, and find the equivalent fraction over 100. For example, say you have the fraction 10/50- you can put that over 100 by multiplying the numerator and the denominator by whatever will get them to equal 100. In this case you multiply 50 by 2, which means that you also have to multiply 10 by 2. That would get you the fraction 20/100 or 20% which is .20 in decimal form. Those are the two ways to convert a fraction to a decimal.
If I was working in a restaurant trying to find the better deal on two items I would use ratio to do it. I personally think that ratio is maybe a longer way to solve, but it is simpler. It is laid out in a way that is simpler to solve in my opinion. Here is an example...
Let's say I work in a restaurant and we need to buy more salt. There are two choices: I could either buy 5 lb. containers of salt for $12.00 each, or I could buy 8 lb. containers of salt for $16.00 each. How do I figure out which is the better buy? Well I have to set it up as two ratios: the ratios are $12.00/5 and $16.00/8. I need to find out the price per pound of salt for each container, and to do that you just divide $12 by 5 lb. and $16 by 8lb. For the 5 pound container you get 2.4, which means that in that container, each pound of salt costs $2.40. In the 8 pound container you get exactly 2 by dividing 16 by 2, so the price per pound of that container is $2.00. Just by looking at those two prices you see that buying the 8 lb. containers is cheaper since it has a lower price per pound of salt. This is how you use ratio to solve a problem like that!
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