We now have the general

tools to really tackle any multiplication problems. So in this video I’m just going

to do a ton of examples. So let’s start off with–

and I’ll start in yellow. Let’s start off

with 32 times 18. Say 8 times 2 is 16. Well, I’ll do it in our head

this time because you always don’t have all this

space to work with. So 8 times 2 is 16. Put the 1 up there. 8 times 3 is 24. 24 plus 1 is 25. So 8 times 32 was 256. Now we’re going to have to

multiply this 1, which is really a 10, times 32. I’ll underline it

with the orange. 1 times 2– oh, we have

to be very careful here. 1 times 2 is 2. So you might say hey, let

me stick a 2 down there. Remember, this isn’t a 1. This is a 10, so we have

to stick a 0 there to remember that. So 10 times 2 is 20. Or you say 1 times 2 is 2, but

you’re putting it in the 2’s place, so you still get 20. So 10 times 2 is 20. It works out. Then 1 times 3. And we have to be very careful. Let’s get rid of what

we had from before. 1 times 3 is 3. There’s nothing to add

here, so you just get a 3. And so you get 10

times 32 is 320. This 1 right here, that’s a 10. 10 plus 8 is 18. So now we just add

up the two numbers. You add them up. 6 plus 0 is 6. 5 plus 2 is 7. 2 plus 3 is 5. Let’s keep going. Let’s do 99 times 88. So a big number. 8 times 9 is 72. Stick the 7 up there. And then you have

8 times 9 again. 8 times 9 is 72, but now

you have the 7 up here. So 72 plus 7 is 79. Fair enough. Now we’re done with this. Let’s just delete it just so

that we don’t get confused in our next step. In our next we’re going to

multiply this 8 now times 99. But this 8 is an 80. So let’s stick a 0 down there. 8 times 9 is 72. Stick a 7 up there. Then 8 times 9 is 72. Plus 7 is 79. 2 plus 0 is 2. Let me switch colors. 9 plus 2 is 11. Carry the 1. 1 plus 7 is 8. 8 plus 9 is 17. Carry the 1. 1 plus 7 is 8. 8,712. Let’s keep going. Can’t do enough of these. All right, 53 times 78. I think you’re getting

the hang of it now. Let’s multiply 8

times 53 first. So 8 times 3 is 24. Stick the 2 up there. 8 times 5 is 40. 40 plus 2 is 42. Now we’re going to have to

deal with that 7 right there, which is really a 70. So we got to remember

to put the 0 there. 7 times 3, and let’s

get rid of this. Don’t want to get confused. 7 times 3 is 21. Put the 1 there and

put the 2 up here. 7 times 5 is 35. Plus 2 is 37. Now we’re ready to add. 4 plus 0 is 4. 2 plus 1 is 3. 4 plus 7 is 11. Carry the 1. 1 plus 3 is 4. 4,134. Let’s up the stakes

a little bit. So let’s say I had

796 times 58. Let’s mix it up well. All right, so first we’re just

going to multiply 8 times 796. And notice, I’ve thrown in

an extra digit up here. So 8 times 6 is 48. Put the 4 up there. 8 times 9 is 72. Plus 4 is 76. And then 8 times 7 is 56. 56 plus 7 is 63. I’m sure I’ll make a

careless mistake at some point in this video. And the goal for you is to

identify if and when I do. All right, now we’re ready,

so we can get rid of these guys up here. Now we can multiply this 5,

which is in the 10’s place. It’s really a 50. Times this up here. Because it’s a 50 we

stick a 0 down there. 5 times 6 is 30. Put the 0 there, put

the 3 up there. 5 times 9 is 45. Plus the 3 is 48. 5 times 7 is 35. Plus 4 is 39. Now we’re ready to add. 8 plus 0 is 8. 6 plus 0 is 6. 3 plus 8 is 11. 1 plus 6 is 7. 7 plus 9 is 16. And then 1 plus 3 is 4. So 796 times 58 is 46,168. And that sounds about right

because 796– it’s almost 800. You know, which

is almost 1,000. So if we multiplied 1,000

times 58 we’d get 58,000. But we’re multiplying something

a little bit smaller than 1,000 times 58, so we’re getting

something a little bit smaller than 58,000. So the number is in

the correct ballpark. Now let’s do one more here

where I’m really going to step up the stakes. Let’s do 523 times– I’m going

to do a three-digit number now. Times 798. That’s a big

three-digit number. But it’s the same

exact process. And once you kind of see the

pattern you say, hey, this’ll apply to any number of digits

times any number of digits. It’ll just start taking you a

long time and your chances of making a careless mistake are

going to go up, but it’s the same idea. So we start with 8 times 523. 8 times 3 is 24. Stick the 2 up there. Now 8 times 2 is 16. 16 plus 2 is 18. Put the 1 up there. 8 times 5 is 40. Plus 1 is 41. So 8 times 523 is 4,184. We’re not done. We have to multiply times

the 90 and by the 700. So let’s do the 90 right there. So it’s a 90, so we’ll

stick a 0 there. It’s not a 9. And let’s get rid of

these guys right there. 9 times 3 is 27. 9 times 2 is 18. 18 plus 2 is 20. And then we have

9 times 5 is 45. 45 plus 2 is 47. I don’t want to

write that thick. 47. Let me make sure I did that

one right, and let’s just review it a little bit. 9 times 3 was 27. We wrote the 7 down here

and put the 2 up there. 9 times 2 is 18. We added 2 to that,

so we wrote 20. Wrote the 0 down there

and the 2 up there. The 9 times 5 was 45. Plus 2 is 47. You really have to make sure

you don’t make careless mistakes with these. Then finally, we have to

multiply the 7, which is really a 700 times 523. When it was just an 8 we just

started multiplying here. When it was a 90, when we

were dealing with the 10’s place, we put a 0 there. Now that we’re dealing with

something that’s in the 100’s, we’re going to

put two 0’s there. And so you have 7– and let’s

get rid of this stuff. That’ll just mess us up. 7 times 3 is 21. Put the 1 there. Stick the 2 up there. 7 times 2 is 14. 14 plus our 2 is 16. Put the 1 up there. 7 times 5 is 35. Plus 1 is 36. And now we’re ready to add. And hopefully we didn’t make

any careless mistakes. So 4 plus 0 plus 0. That’s easy. That’s 4. 8 plus 7 plus 0. That’s 15. Carry the 1. 1 plus 1 plus 1 is 3. 4 plus 7 plus 6. That’s what’s? 4 plus 6 is 10. It’s 17. And then we have 1 plus 4 is 5. 5 plus 6 is 11. Carry the 1. 1 plus 3 is 4. So 523 times 798 is 417,354. Now we can even

check to make sure. And so this is the

moment of truth. Let’s see if we

have– let’s see. 523 times 798. There you go. Moment of truth. I don’t have to

re-record this video. It’s 417,354. But we did it without the

calculator, which is the important point.

To do it in Hex, you would have to memorize your 16 times tables in hex (and convert to and from decimal to hex). Would take up less space on the paper. Not clear if it would be easier.

Khan, when you say 10 times 2, you should also say 10 times 3. make it simple !

your #1 fun

I LOVE THIS GUY IS SO AWSOME

@Nile1147 i Agree with you

🙂 Thank You! 🙂

When doing the 99×88 Sum, Why when doing the first 9×8 does he put down the 2 and carry on the 7… I always though you carried on the smallest number and put down the largest…. That's really confusing me ;(

U just saved me from my teachers<3

i love how he makes this so easy….lets hope when i get the decimals is this easy and fun!

i want to master arithmetic so i will watch this again next week

wow very cool this math is easy now!!! It use to be hard but now its easy!

yay i finally mastered this

its great :D,s!

If you actually know what hexadecimal is, then why are you watching a video about multiplying multiple-digit numbers?

What your actually doing is multiplying every number with every other number, but your teachers don't want you to know this because you might accidently remember it when you get to combination theory and multiplying binomials.

I think Sal should do an outtakes video edit. I think he probably has some funny clips that didn't make it.

I dont know i just dont get it.. helps though.

that's how my mom taught me 53 years ago. I'm becoming more & more convinced that my folks had something up their sleeve that worked & turned out geniuses, thii they were destroyed by the invasion by the west. & Mr. Khan & I share the same heritage & genetic material as far as the geographi specificity of the DNA is concerned.

Khan academy or con academy?

Is there a name for this method of multiplication?

Whats the software that you use ??

And by the way thnx

worthless and idiotic good for primary class students

Thank you so much!^^ This will hopefully help me for my.exam tomorrow!:) I gotta watch this video again when I'm at school waiting to get into class.

I love your work with with my kids.

Boring!!!! ! !!!!!!!!!!!!!!!!

Frankie O'B, this is a late reply and not even directly to your comment since YouTube apparently thought that was a bad idea, but let me answer your question anyway. What you actually are doing is carry the biggest number, because you carry it to the next place — e.g. from the ones place to the tens place. The 7 that you're carrying actually represents 7 tens, as it comes from 72 which is 70 + 2. So you leave the 2 in the ones place where it belongs, and you put the 7 in the column for the tens place.

You probably got confused because you got a lot of 6*3 and 5*5 where you get answers like 18 and 25, where the first number (the tens, the one that you carry) is smaller than the second (the ones, the one that you leave in place). Since tens are bigger, they often times go up less quickly, after all. Just remember that the actual rule is to carry the number for the biggest 'place' (tens over ones, hundreds over tens). Technically, in that sense, you're always carrying the BIGGEST number — 70 rather than 2, 10 rather than 8, or 20 rather than 5.

Hope that helps.

Luv khan academy

7*5 = 35

The first problem is wrong 8x 32 is 246 not 256

The over all answer is 566 not 576

Thank you so much, I finally get how to multiply triple digits! I kept getting the wrong answer but I went step by step and I got the write answer

hey

Your the best Mr Khan you helped my daughter so much ever since she's been watching her videos. Mr Khan I don't know what I could do without you.

bobbu

Is that program you use to draw out the numbers available for free by any chance? Would help me a ton

Hi how do I multiply 4 x pi x 3 without a calculator

this helped me a LOT!!!!!!!!!

I do think you should have taught us when we have to use zero though

I do think this is a little bit boring to

https://www.khanacademy.org/math/cc-fifth-grade-math/cc-5th-arith-operations/cc-5th-multiplication/v/multiplication-6-multiple-digit-numbers

You helped me multiply. THANK YOU!!!

very easy

how was double digit multiplication invented and who invented it

Good job

Thank you!

😺✌🏾️

My family loves you guys! Thanks!!!! 😸👍🏽

i saw a mistake on 5:28 he shouldnt put 0 down he should put 3

Thanks

you really helped me

you help me a lots think you

I like Khan Academy. He teaches me many things and makes it understandable.

This helped my little brother

I will hate math forever

you helped me sooo much

Does anyone know what app or program he is using to do his presentation? Thanks.

Thank you for helping Khan!

You helped me a lot I don't know what to do without you Thank youuuuuuuu!!!!🌊🌈😊😊😋

M.R khan you helped my son so much you made my sons life so muck better than it was

thanks dude i never new how to do this it would take me forever to do this and i would cry if i got it incorect and also get realy angry your the best dude

whos here in 2017

thanks idid not understand then i got just looking at your name tag THANKS YOOOOOOOOOUUUUUUUUUU!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I just wanna say thank you,you help me so much!!!!

Ok BAIIII

Khan acadamy do you know 1346556456592838 x 999999999999?

cool vid i liked it

I subbed!

Finally someone who explains it and shows it very good.

Khan Academy and mathantics are the best channels for math help.

Thank you, you helped very much and its great education for free, and that is rare. 😀

My teacher recommended this to me and it helped so much… thank you!

you made a mested up on the last one on the

My math teacher absolutely loves you we watch at least 1 on these everyday day before we do our work

This is helping me a lot

You're a legend

THANKS HELPED ALOT

I think that we should not put 0 we should put X

Hi I’m in 4th grade and this really helped me thank you

yay thanks now I’ll no a little bit for school tommorow

you said and ut were not using decimals XD LOL

*WE

my teacher is always sayin "don't say and we are not using decimals"

My math I get 100 every math test

Do you kids 8-10 years old require expensive tuition on the weekends when you have resources like khans academy ??

I swear your the only reason I passed Math. Thankyou. I owe you my job

What about 378 x 9???

I just found you thanks to a friend’s recommendation. With this video you helped me understand 3 digits multiplication I’ve never understood in school! I’m 36 😂 thank you and please don’t ever stop what you’re doing, amazing work!! You have a new subscriber 😀

this helped me thanks 🙏🏻

Can some help me with math with digits

Thx!!!!

I have to watch this for homework then do 10 years of math

yo this is so helpful ill finally get an a on my homework!

when I first started khan academy I couldn't even subtract three digit numbers now I can multiply them!

This really helped me a lot! Thank you Khan Academy!

Did this intermediate and beginning of high school and then completely forgot about it smh

Esey

Great!!!!!!!!!!

This is what my bro need to watch.