How to Divide Decimals by Decimals

Hey Friends! This week we are going to divide decimals by decimals! What does it mean to divide?

Yep! Make equal parts or groups! 

To divide decimals correctly, you have to remember 3 things.

1. Use graph paper or turn your notebook sideways to line up your numbers correctly.
2. Move the decimal, so that your divisor is a whole number. What you do to the divisor, you do to the dividend.
3. Use your mad long division skillz to solve. 

Here's a quick video lesson...

One more example...

 

Click here for the whole lesson!

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!

The Power of Ten!

This week we're SUPER excited to learn about the SUPER Power of Ten! Using exponents is an efficient way to write numbers that have a few too many zeeeeeros.

The exponent (or power) tells us how many zeros are in the number when the base number is 10.

The image below has a place for everything with everything in its place. The base can be any whole number, but today we are only focusing on the POWERS of TEN!

Here are the vocabulary words for this lesson: 

powers of ten

base number 

exponent

Multiplying with powers of ten is SUPER fun! When multiplying a decimal number by a power of ten, just count how many zeros you have and move the decimal to the RIGHT! If you use exponents, they'll tell you how many places to move the decimal. Just ask 'em.

Games and other resources:

Splash Learn

OnlineMathLearning.com

The Math Page
Math is Fun 

Click Here for more! 

Click the image below for a catchy Powers of 10 song! 

Powers of 10 Song Lyrics:

Chorus

To find the power of ten

Look at the exponent

Take your pencil and then

and write that many zeros, let’s do it again

To find a power of ten

Look at the exponent

Take your pencil and then

Multiply that many tens

The base number is 10

2 is the exponent

10 to the second means 10 x 10

This power of ten is 100

Again the base number is 10

but now 3 is the exponent

it equals 10 x 10 x 10

The third power ten is 1000

The base number is 10

4 is the exponent

it's 10 x 10 x 10 x 10

The fourth power is 10,000

Again the base number is 10

5 is the exponent

write five tens and multiply them

and you’ll get 100,000

With a power of ten we can multiply or divide

Dividing slides left, multiplying slides right

The powers the number of places…

Slide the point that number of spaces

One hundred five and nine thousandths

Times ten to the third, the three represents

The decimal point sliding right three times,

The products one hundred five thousand, nine.

Now let’s divide by ten to the third

Slide three places left, or in other words

This number is now one thousand times less -

POWERS OF TEN ARE THE BEST

Using powers of ten is the norm

When writing numbers in expanded form

Split the values apart bit by bit

To see the value of every digit.