Percent and Fractions (Simplifying Math)

hello this is mr. Buffington and we are looking at percents and fractions today calculating percents and changing between fractions and percents what you can expect to see in this lesson is that we'll go from a fraction to a percent we'll then turn around and do a percent into a fraction and as a bonus fun part will also do the percent of an amount like 15 percent of 100 is whatever and we'll calculate that as well it's pretty quick let's talk about fraction to a percent first off a fraction means out or I'm sorry another fraction a percent means out of 100 that's what it means so you if you write it as a fraction it's simply over 100 something over 100 that really is a terrible color I apologize for that I'll do better next time so if I'm going to change 7 over 20 into a percent I could simply change it to a fraction over 100 now this works sometimes so I'm going to show you this method because it's really fast when it works then when it does not work I'll show you another way to figure out the percentage as well but if we're trying to calculate the percent seven over 20 as a percent I would say it equals what over 100 what is it out of 100 because remember a percent is something out of 100 so I look at this number and I say 20 to be made into 100 what do I do this is I've called it in the past my what happened method what happened to 20 that made it into 100 well 20 times 5 is 100 so I would do the same on the top and bottom and that would give me 35 over 100 all right so 7 over 20 is 35 over 100 which means it's 35 per cent all right let's look at another one here real quick just to I'm just a kind of whoops get an idea 13 out of 50 is what over 100 I look at this fraction and you can solve using cross multiplying here as well but I'm gonna use the what happened method just to keep things pretty straightforward what happened to 50 to get me to be 100 while 50 times 2 is equal to 100 so I also multiply the top times 2 13 times 2 gives me 26 over 126 out of 100 is print 26 per cent so that's one method if you can easily see Oh my fraction the denominator can easily be made into 100 so if this is a fraction out of 20 25 10 something like that this method might be a good shortcut now for all other fractions you can solve it in this way like I said using cross multiplying or you can just do division so I'm going to show you how to do this using division this will work for every single fraction it could have worked we could have used this method for our previous fractions 7 over 8 a fraction of 7 over 8 mean 7/8 that's what a fraction means so just go ahead and divide it you can't it won't go into 7 because 8 is greater than 7 so we're gonna add the zero there and how many times does 8 go into 70 it goes in 8 times 8 times 8 is 64 we subtract and get 6 and then we bring down that zero how many times does 8 go into 60 goes in 7 times 7 times 8 is 56 then we subtract we'll get 4 bring down the zero how many times does 8 go into 40 five times and and then we finally get a nice even number now I did not show you all of the I showed you all of the steps but I didn't explain all of the steps thoroughly this is doing long division if you're not familiar we're doing long division there are other videos that show you how to do all of the steps for that but this is sort of a prerequisite that you would know how to do long division say 7/8 is equal to zero point eight seven five now 0.875 this is a decimal and converting between a decimal and a percent is just about the easiest thing that we can do we can do it in a couple of different ways but first off just remember that the number here in this case seven is in the hundredths column that is eight seven and five the seven is in the hundredths column so it's 87 hundredths and and the five okay so this number here is going to be the one that that we can kind of move the decimal over to there and that would be instead of being 87 hundredths it would be 87 percent and then that decimal of 0.5 off the end basically you're moving the decimal two places so you can remember it in lots of different ways you can remember it as 87 hundredths oh that means 87 over 100 that's 87 percent and then we've got 0.5 on the end there or you can just move the decimal over two places you could also take this this decimal and multiply it times 100 any of those methods work but for me the simplest way is just move the decimal over two places remember that your second place is the hundredths so that's where you want to stop for percents percents are hundredths okay so that is how you would do using it the division method just divide the number and move the decimal over two places to the right pretty straightforward all right the next part is when we are converting from a percent into a fraction percent remember means out of 100 it means a fraction over 100 still a terrible color for this rectangle I will get better by the end of this video don't worry alright so if I have the number twenty percent that means 20 over 100 there we go converting from a percent to a fraction is super easy just put it over 100 there is one thing that we need to remember and that's that we have to simplify the fractions into lowest terms all right we do have to reduce our fractions to lowest terms so 20 percent means 20 over 100 we reduce this or simplify it into lowest terms to do that we divide by our greatest common factor in this case that's 20 20 divided by 20 is 1 100 divided by 20 is 5 so 20 percent is equal to 1/5 we've converted from a percent into a fraction all you do is put it over 2 over 100 and simplify it I've got a sample here for you go ahead and pause the video try and convert this percent into a fraction and now I'm going to show you how I would do that I would start with my first step put it over 100 then I have to remember to simplify 32 over 100 I need to divide the top and bottom of this fraction by the greatest common factor greatest common factor in this case is 4 32 divided by 4 gives me 8 100 divided by 4 gives me 25 32 percent is 8 out of 25 that's it converting percents into fractions look like that sometimes you'll get them a prime number like or a number that does not have any common factors with 100 like 13 13 percent would just be 13 over 100 you would not need to simplify it down it's done so converting from a percent into a fraction is actually one of the easier things that we need to do with percents our final step is that we're going to find the percent of an amount we have to remember two things with this first off the word of means multiply that's that is going to be the case for this and it will help us out if we remember the word of means multiply also point zero one is 1/100 or 1% here's another example of that point 1 2 is 12 hundredths or in other words 12% we talked about that earlier just want to emphasize that point because that is going to make our life a lot easier if we remember that that second number on the right of the decimal that's the number that we take for our percent all right so if we're asked to calculate 15% of 80 this is easy if we just change the words into numbers so this can be easily written as a math question I like to color code things I think it makes it a little bit easier so 15% that can be written as 0.15 of can be written as multiplication and 80 is 80 so now we have a simple math question of 0.15 times 80 this is the easiest way in my opinion of converting a percent of an amount to actually getting the number now I just calculate 0.15 times 80 is equal to 12 that means 15 percent of 80 is 12 let's do another one here again you can pause the recording and try this one out what's 12% of 93 we're gonna write it out as a math question I'm going to color code 12% is 0.12 of is multiplication 93 is 93 so 0.12 times 90 3 gives us 11 point 1 6 that's it so finding the percent of an amount if you're asked to find some percent of an amount just write it out in a simple math question and you're done so what did we expect at the beginning we expected to talk about fractions 2 % % 2 fraction and calculating the percent of amount how'd we do I think we covered all of those topics I hope it was help for you have a wonderful day

Channel: Eric Buffington

Views: 67,675

Rating: 4.6702509 out of 5

Keywords: Fraction, decimal, percent, mathematics, math, lesson, converting, between, basics, help, learn, need, tutor, teacher, tutorial, fun, quick, easy, understand, college, foundations, middle school, high school, school, academy, Buffington, Simplifying Math

Id: 8loMuMu6KHU

Length: 11min 14sec (674 seconds)

Published: Wed Jan 04 2017