Video instructions and help with filling out and completing What Form 2220 Multiply

Instructions and Help about What Form 2220 Multiply

In this lesson we're going to talk about multiplying but using expanded form to multiply our numbers together and to do that you might want to look at the video on expanded form just to refresh your memories to what that is but if you're ready to jump in what we're going to do is we're going to take this example problem I'm going to walk you through it you can then pause the video and try the other two problems on your own or you can go with me and we'll do them all together so I have 45 and 45 in expanded form it is 40 tens plus five ones so it looks like 40 plus five and I have 12 which is one group of ten plus two ones so I have ten plus two and to multiply this out I'm going to do some cross multiplying from my top numbers to my lower numbers so I'm going to do 40 times 10 and 40 times two okay and then I'm also going to do five times ten and five times two so as you can see I took this number and multiply it against both of my lower numbers and took this number and I also multiplied it against both of my lower numbers and I'm going to figure out what the products of these are so 40 times 10 is 440 times 2 is 80 5 times 10 is a 50 and 5 times 2 is 10 and now I can add up my products to get a total sum at the bottom and probably I should do is line these up just make sure I don't make any errors so I'm going to rewrite them over here but line up on my place values all right so I have my zeros down zero plus 8 plus 5 is 13 plus one more is 14 here my one one plus four is five so my answer for 45 times 12 is 540 and then you can use lattice multiplication or standard multiplication to make sure you did it right to check your work all right this time you can go ahead and pause the video and try these two on your own using the same strategy that I just showed you or we can work them out together same thing I'm going to take 36 and write that in expanded form and that is going to be 30 plus 6 and 15 written out in expanded form 10 ones and five I'm sorry 10 one 10 and five ones so 10 plus 5 and I'm going to do the exact same thing multiply both my top numbers I give the bottom numbers so 30 times 10 and then 30 times 5 and then 6 times 10 and 6 times 5 go ahead and get some products here so 30 times 10 is 330 times 5 is 156 times 10 is 16 as you can see I'm lining up my my numbers a little bit better at this time and 6 times 5 is 30 and add these up bring my zeros down 5 plus 6 is 11 plus 3 more is 14 carry my one up here 1 plus 3 plus 1 is 5 Wow 540 and then we're going to do this one over here I have 72 which is 7 tens plus 2 ones I have one group of 10 plus 9 ones so that's 72 and 19 written out in expanded form now to multiply we're going to do so many times 10 and 70 times 9 and then 2 times 10 and 2 times 9 okay now to get some products so many times ten is seven hundred seventy times nine is 632 times ten is twenty and 2 times 9 is 18 now we're going to go ahead and add those up get a song which will give us our answer so we have an 8 in the ones place after I add all those numbers together 3 plus 2 plus 1 is 6 and then 7 plus 6 is 13 fine come on here so my answer 472 times 19 is 1368 and that is using expand upon and multiply