[Music] hi and welcome to this corporate maths primary video on fractions of amount now you probably already know how to work out a half of 20 but a half of 20 is 10. and the reason that a half of 20 is 10 is that if you have 20 you share equally between two that each of them gets 10. so a half of 20 is 10 and you can find it just by dividing it by 2. so if i wanted to work out half of 14 well 14 divided by 2 is 7 just sharing it equally between two and again a half of 60 well a half of 60 is 30 because again if we do 60 divided by 2 we get 30. right now let's work out a third of some numbers so a third of 15 well again if i share 15 equally between three people or share it equally between three i get that each person gets five or each item is five so a third of fifteen is five and again the way to work that out is we just take our 15 and we divide it by three so if you want to work out a third of something you divide by three so 15 divided by three is five next a third of 30 well a third of 30 is going to be 10 because 30 divided by 3 is 10 and finally a third of 18 well a third of 18 is 6 because 18 divided by 3 is 6. so if you want to work out a half of something you divide by 2 if you want to work out a third of something you divide by 3. so if you wanted to work out a quarter or something we were just going to divide by four so 100 divided by four uh well we could half and half it again to get 25 or we could do 100 divided by four just using up our shelter method uh four into one doesn't go remainder one four into ten goes twice remainder two and four into twenty goes five times so a quarter off of one hundred is twenty five so to get a quarter or something you just divide it by four next one one-fifth of 35. well again if we want to work out a fifth of 35 we're just gonna divide it by five so 35 divided by five is seven and finally one-tenth of 80 well if we want to work out a tenth of 80 we just divided by 10 so 80 divided by 10 is it so that's quite nice if we're trying to work out a half or a third or a quarter or whatever we just divide by the number on the bottom of a fraction in other words the what we call the denominator we just divide by the number on the bottom of the fraction as long as it's got a one on the top but what if the fraction that we want to find out is something else maybe like two thirds or fifteen well again we know that a third of fifteen is five because if we do fifteen divided by three we get that if you share equally amongst three each person gets five well if i want two-thirds well that would be two-thirds well altogether that would be ten now a quick and simple way of doing that is to get our 15 and divided by three to work out what a third is which is five and if we wanted two thirds that's two lots of five you just times it by five or by two so two times five is equal to ten so if we want to work out a fraction of a number we divide by the bottom and times by the top and so for instance if i wanted to work out three seven oh sorry if i wanted to work out if i wanted to work out three sevenths i would divide by seven and times by three now the ones we looked at earlier maybe like a quarter we divided by four but there's no point in times by one because if you times by one you just get what the quarter is anyway okay so let's have a look at some questions so our next one is three fifths of twenty so we're going to take our 20 and work out a fifth of it so a fifth of 20 20 divided by five would be equal to four and we want three fifths so we're just going to take our four and we're going to times it by three to work out what three fifths of three and that would be twelve so three fifths of twenty is twelve and our next one 2 9 of 36 again we're going to get our 36 and we're going to divide it by 9 to get what one-ninth is so that's going to be four and then we want two lots of that so we're going to do four times by two to work over two nines is and that's to be equal to 8. so to work out a fraction of a number you just divide by the bottom and times by the top and sometimes you might need to maybe use like the bosch shelter method or you know to do the division so here we've got two-fifths of 600 so again to get two-fifths of something we're going to divide it by five first of all so 600 divided by five so our five into six goes once remainder one five into ten goes twice and five into zero goes zero times so one-fifth of 600 is 120 but i want two uh two-fifths so i'm going to times 120 by two and if you double 120 we get 240. so that would be 240. that's it so if you want to work out a simple fraction like a half or a third or a quarter or a fifth you just divide by the number on the bottom of the fraction if you wanted a fraction of a number for instance you know three-sevenths or two-thirds you just divide by the number in the bottom of the fraction and then times where the number on the top of the fraction and that's it