Video transcription

So how does one change a ratio into a decimal? Hi I'm Jimmy Chang and I have been teaching college math for nine years and we are here to explore exactly how to do just that. If you know what a ratio is you probably notice that more often than not it is indeed a fraction so what we are actually doing is we are taking the ratio and calling it a fraction and then we are converting it to a decimal. If you are familiar and pretty solid with your long division skills, then that is pretty much all you need so here is an example. Suppose you want to take the ratio one over 4 which is 1/4 and you want to convert that to a decimal form. Now this really becomes a long division exercise because the numerator is always going to be on the inside of the division and the denominator which is the four here is always going to go on the outside. Now you and I both know that four does not go into one, however, what you can do is to figure out what the actual value of the decimal is put the decimal symbol right after the one and for your answer just put a decimal right above it so your answers will line up easily. Now since you know that four does not go into one you know there is going to be a 0 so we know it is going to be 0 point something. Now to figure out the exact value you put in as many 0's as you need to underneath until you get the answer or if you see a pattern. So for example I am going to put a 0 right after the 1 and then see what 4 goes into 10 is going to be. Well as you know 4 goes into 10 twice, then just do like you would with long division. 2 x 4 is going to give you 8, do the subtraction, don't worry about the decimal right now. 10 - 8 is going to give you 2. Now we know 4 doesn't go into 2 but you don't have an exact answer yet so you are going to try for one. Now add another 0 and just like long division, bring down the second 0 and then repeat. 4 goes into 20 how many times and as you know that is going to be 5 and then 5 x 4 is going to give you 20 do the subtraction again and you will see that you have a remainder of 0 and as a result you have an exact answer so in this case 1/4 is equal to 0.25 as the decimal. So if you know how to convert a ratio into a long division problem the answer will give you a decimal. So I'm Jimmy and that's how you convert a ratio into a decimal form.