welcome to fifth grade math with mr. J in this video you're going to learn how to multiply fractions whether it's a whole number by fraction or a fraction by a fraction and as you can see there are four problems on your screen we're going to do these four problems together and then you'll try four on your own over at the mastery check the link to the mastery check is down in the description by the way so for number one we have six times one-third so a whole number times a fraction now when we multiply fractions all we need to do is multiply straight across so numerator times numerator and denominator times denominator so the first thing we need to do with the six is make it into a fraction whenever you have a whole number you can make it into a fraction by putting it over one that way you have a numerator and a denominator bring down the multiplication sign and the one-third now we multiply straight across numerator times numerator denominator times denominator so 6 times 1 is 6 1 times 3 is 3 so our answer is 6 thirds but that's an improper fraction meaning the numerator the top number is larger than the denominator the bottom number so you never leave an answer improper so how to convert it out of improper fraction we need to divide the numerator the top number by the denominator so 6 divided by 3 that's going to give us a whole number here so how many whole groups of 3 can we pull out of 6 well 2 now once we do that is there anything left over is there a remainder no so our answer is 2 so 6 times 1/3 is 2 now I want you to take a look at this answer compared to our problem because normally we think when multiply two numbers we should get larger and value our answer should grow in value right if you did six times two we get twelve but here we started with us six and we ended up with the two and that's because we multiplied by a fraction that's less than one hole so whenever you multiply by something less than a hole you actually your answer is going to decrease in value from what you started with so let's take a look at number two we have 12 so it's a whole number let's put it over one and we multiply by three-fifths so go straight across 12 times 336 one times five is five so 36 fifths so what we need to do now that's our answer but it's improper so we need to divide the numerator by the denominator so 36 divided by five so how many whole groups of five can we pull out at 36 and the answer is seven holes so that's our whole number here but we didn't hit 36 exactly we have a remainder or something left over so seven times five is thirty-five subtract to find out what the remainder is and it's one so that one is actually going to be the numerator of our fractional part of this mixed number a mixed number has a whole number and a fraction so our remainder is the numerator and we keep the denominator the same so we bring that five over so 7 and 1/5 so again we started with 12 and we multiplied by something less than a whole so our answer actually decreased in value relative to what we started with in the problem and that's okay because we multiplied by something less than one hole so number three we have 3/4 times two Thirds all right straight across three times two is six and four times three is twelve so our answers six twelfths now that fraction can be simplified it's a proper fraction but we have a greatest common factor between the 6 and the 12 that we can break down or simplify this fraction into its lowest terms and that greatest common factor is 6 so let's divide both of these by 6 6 divided by 6 is 1 and 12 divided by 6 is 2 now that fraction cannot be broken down any more the only common factor between 1 & 2 is 1 so we are done the answer to number 3 is 1/2 all right number four we have 1/7 times 2/3 straight across 1 times 2 is 2 and 7 times 3 21 so we get 2 over 21 now the only common factor between 2 and 21 is 1 so we are simplified here that's as far as that fraction can break down so we are done 2 over 21 all right there you have it so that's multiplying fractions you just multiply straight across numerator times numerator denominator times denominator and then see if you can simplify your answer thanks so much for watching and until next time peace you