ShmoopTube

Where Monty Python meets your 10th grade teacher.

Search Thousands of Shmoop Videos

Long Multiplication 1788 Views


Share It!


Description:

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.

Language:
English Language

Transcript

00:04

Long Multiplication, a la Shmoop. Ah, the holidays. A time to come together

00:10

to wage war over politics and tell the kids they're disappointing.

00:14

Jack and Bunny Rabbit come from a very fertile family.

00:17

Which is why figuring out how much carroturkey to cook for Bunsgiving makes Bunny completely

00:18

hare-brained. The Rabbits have 49 children, and there are

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?

Up Next

Operations with Rational Expressions
8687 Views

It's impressive that these expressions are able to stay so rational even when they're having operations performed on them.

Related Videos

Numbers and Operations: Elementary Number Theory
605 Views

Jack and Jill went up the hill to fetch a pail of water. But what happened when they got up there? They’ve been gone an awfully long time…

SAT Math 7.3 Algebra and Functions
318 Views

SAT Math 7.3 Algebra and Functions

SAT Math 6.4 Algebra and Functions
486 Views

SAT Math 6.4 Algebra and Functions

Word Problems with Addition and Subtraction
4464 Views

Sometimes, we just want fewer y's...or more x's. That's why it's great to know how to add and subtract variables. In real life, though, we try to a...