today we're learning how to use fact families to solve multiplication and division problems now a fact family can be shown as this triangle where the numbers are connected by either multiplication or division let's think about the numbers 5 4 and 20 because you already probably know the math facts related to these but let's pretend I did it and I wanted to figure out what 5 times 4 equals well you could think to yourself in this equation I've already used a 5 and I've already used a 4 the number from my fact family that's missing is the 20 and you would be correct you could put it in and write the 5 times 4 equals 20 you could do it the opposite way to 4 times 5 if you want to figure out what this is well you've used your 4 you've used your 5 but the number that's missing is the 20 so 4 times 5 also equals 20 we can use this not just for multiplication but for division let's say I wanted to figure out what 20 divided by 5 equals well in my fact family I can see that my equation has a 20 in it and it has a 5 in it so these two numbers are missing the 4 20 divided by 5 does equal 4 you could also check with 20 divided by 4 when you do this you've used your 20 and you've used your 4 so the answer must be the 5 20 divided by 4 equals 5 now let's practice with fact families together let's look at the fact family that has 6 7 and 42 well this means that 6 times 7 equals what we'll we've use the 6 in our equation and we've used the 7 so they're related to the 42 the missing piece is 42 what is 7 times 6 equal well we've used the 7 we've used the 6 so it must be 42 as well 7 times 6 equals 42 we could also use this to solve a division problem we could figure out that 42 divided by 6 equals what what we've used our 42 in the equation we can see that we've used a 6 so the answer is the third number the sap forty-two divided by 6 equals seven and the final fact of our fact family is what does 42 times 7 equal well we have our 42 and our 7 in the equation so what's missing is the 6 42 divided by 7 equals 6 now it's time for you to practice on your own select the four equations that match the fact family with 8 9 and 72 well first you'll have that 8 times 9 gives you 72 you'll also have that 9 times 8 gives you 72 you could do the opposite with division 72 divided by 8 gives you 9 and 72 divided by 9 gives you 8 here's your last one what are the 4 equations for the fact family with a five a seven and a 35 well this fact family has the equation 5 times 7 equal 835 7 times 5 equals 35 35 divided by 5 equals 7 and lastly 35 divided by 7 equals 5 so from today remember fat families show how numbers relate to each other with multiplication and division and that you can use fact families to find math facts more easily [Music]