Multiplying Decimals

Remember, when you multiply, you are really just adding equal groups!

When you multiply whole numbers by whole numbers (4 x 3) you are making an array of equal groups, to form a rectangle.

When you multiply a whole number by a decimal, you are also making equal groups!

You can use the same strategy when multiplying decimals by decimals. 

Arrange your base ten blocks to show the 2 factors (length x width). 

Fill in any blank spots to complete the array (rectangle). 

What's the area of the complete model?

(click on the image it get a closer look)

Here is a helpful video that shows how to solve decimal multiplication 

problems using area models...

Finally, as we learned in class this week, we can also use the algorithm to find the product!