Long Multiplication

What do you do when you have to multiply large numbers but you can’t use a calculator? Long multiplication, of course. This video covers how to do a long multiplication problem to solve an intimidating math problem. It’s really a lot simpler than it looks if you just take it one step at a time—and always remember to carry your numbers.

Basic OperationsMultiplication and Division
LanguageEnglish Language

Transcript

00:20

37 grandchildren per child. How many children and grandchildren are there?

00:26

If there are 49 children and each has 38 kids of their own, we can multiply 49 by 38 to

00:32

get our answer.

00:32

<<Jack voice>> "This looks like a job for Multiplication Man!"

00:36

To solve this multiplication mystery,

00:39

we're going to work backwards through 38's digits, first multiplying by 8,

00:44

then multiplying by the 3, which is actually 30.

00:48

First find 8 times 49. 8 times 9 is 72. Write the 2, carry the 7.

00:57

8 times 4 is 32, plus the carried 7 is 39.

01:03

When we write down 39 we get 392. Next multiply 3 by 49.

01:09

Repeat the steps we just did, multiplying 3 by 49, but this time write a zero before

01:15

you begin, since our 3 is actually a 30.

01:19

3 times 49 comes out to 147, so we get 1,470.

01:37

Next add 392 plus 1,470.

01:41

2 plus 0 equals 2.

01:44

9 plus 7 equals 16, so we write the 6 and carry the 1.

01:49

3 plus 4 plus the carried 1 equals 8. And 1 plus nothing equals 1.

01:56

Finally, you get our answer, 1892. Success!

02:01

That's a lot of hungry rabbits to feed. Bunny, are you going to have that carrotturkey done

02:26

in time for dinner?