If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

### Course: Class 3>Unit 4

Lesson 5: Multiply 2-digit numbers with area model

# Multiplying with area model: 16 x 27

Sal uses an area model to multiply 16x27. Created by Sal Khan.

## Want to join the conversation?

• Is it permissible to use this area concept by subtracting a 'negative' area?
For example, using our problem of 16 x 27, we could actually make an area of 20 x 27. We can then subtract an area of 4 x 27 to yield our answer.
We can easily calculate 20 x 27 = 540, and then subtract a similarly easy calculation of 4x27=108 → 540-108=432.
• Good point, I think you are absolutely right. We can even set up a diagram like Sal has done, using negative numbers in one or both sides of the multiplication.

Eg. Using (30 - 3) for 27, and (20 - 4) for 16 in the diagram below
We get 600 - 120 - 60 + 12 = 432

``       30      -3   .______________.   |        |     |   |        |     |20 |  +600  | -60 |   |        |     |   |________|_____|   |        |     |-4 |  -120  | +12 |   |________|_____|``
• 30 -3
.____________.
| | |
| | |
20 | +600 | -60 |
| | |
|______|_____|
| | |
-4 | -120 | +12 |
|______|_____| this is my area model khan sir
• This is an interesting way of using area models to multiply. This is most useful for multiplying numbers that have high digits.
• Can you explain me how to do the area model negative numbers if it is possible?
Also what do you mean when you say subtracting a 'negative' area?
• I don't know what it means by subtracting a negative area, but the question basically says to multiply 16 by 27 which is 432. This probably doesn't help but I hope it does.
• What would an aria model for 95 / 6 = ?

/ = divided by
• An area model is shown. Which expressions show how to multiply 4 1/4×2 3/5 using partial products? Label the model with the correct expressions.
• I did not know you got energy points for watching a video
• I think the points are to hipe you up