Road Trip!Road Trip!Using Multiplication and Division of Using Multiplication and Division of

DecimalsDecimals

Javier is planning a road trip from Javier is planning a road trip from Houston to El Paso with three friends. Houston to El Paso with three friends. All agree to equally split the cost of the All agree to equally split the cost of the trip.trip.

Your job will be to help Javier organize Your job will be to help Javier organize his budget for the trip.his budget for the trip.

Review of Decimal MultiplicationReview of Decimal Multiplication

We will use an easyWe will use an easy3 step process to help 3 step process to help refresh our memory. refresh our memory.

Let us consider the example, Let us consider the example, 8.2 X 5

Step 1Step 1

Count the number of digits to the right of the Count the number of digits to the right of the decimal point.decimal point.

8.2 X 5

One number to the right of the decimal point.

Step 2Step 2

Multiply like there was no decimal (we Multiply like there was no decimal (we moved it to the right to get whole numbers)moved it to the right to get whole numbers)

8 2 X 5 41 0

410 = 410.0

41 0 0

Step 3Step 3o Use the number of digits you counted in Use the number of digits you counted in

Step 1 to place the decimal back where it Step 1 to place the decimal back where it belongsbelongs

o We counted 1 digit in Step 1, so we move We counted 1 digit in Step 1, so we move the decimal point by 1 place to thethe decimal point by 1 place to the left left

.

.

Before We Begin:Before We Begin: Review Decimal Division Review Decimal Division

16.4828.2

Multiply both the divisor and dividend by the smallest power of 10 that is needed for the divisor to be a whole number.

164.8282Remember if we multiply both the dividend and the divisor by 10 it does change our answer… ½ * 10/10 = 10/20 = ½!!!!

-164 0 8

8

2 .0

Now, Now, Divide like normal: Divide like normal: For Example,For Example,

164.82 82

0

- 0

1

- 822

The distance between the twoThe distance between the two cities is 822.5 miles. cities is 822.5 miles.

Javier wants to calculate how Javier wants to calculate how much money he should expect to spend for much money he should expect to spend for gas during his trip. gas during his trip.

Javier’s car uses 32.9 miles per gallon. Javier’s car uses 32.9 miles per gallon. How many gallons will his car consume for a How many gallons will his car consume for a

roundtrip?roundtrip?

Problem 1

What do we want to know?What do we want to know?1) We want to know how many gallons of gas the trip will take!1) We want to know how many gallons of gas the trip will take!

2) The distance was 822.5 miles2) The distance was 822.5 miles And they got 32.9 miles per gallonAnd they got 32.9 miles per gallon

And what information did we get???And what information did we get???

How are we going to set the problem up?????How are we going to set the problem up?????

Miles Miles ____________

Miles Per GallonMiles Per Gallon= GALLONS!!!= GALLONS!!!

822.5 ÷ 32.9822.5 ÷ 32.9

What about for the What about for the Roundtrip?Roundtrip?

To find the total gallons used for a To find the total gallons used for a roundtrip we can multiply by 2.roundtrip we can multiply by 2.

25 x 2= 50 gallons25 x 2= 50 gallons

The hotel room Javier The hotel room Javier plans to stay at costs plans to stay at costs $132.30 a night and $132.30 a night and will accommodate all will accommodate all 4 friends. 4 friends.

How much would each person spend How much would each person spend on the hotel for one night?on the hotel for one night?

See if you can do 2) on your own………See if you can do 2) on your own………

Problem 2

What did we need to do this What did we need to do this time?time?

We take the cost and divide We take the cost and divide by 4!!!by 4!!!

We get $132.30 ÷ 4 = We get $132.30 ÷ 4 = $33.075$33.075

Javier and his friends Javier and his friends plan to go out for pizza plan to go out for pizza one night.one night.

The cost of a pizza is The cost of a pizza is $16.84. $16.84.

How much would each How much would each person pay if one of the person pay if one of the friends doesn’t attend?friends doesn’t attend?

Problem 3

A = 5.613_

On one day Javier is On one day Javier is planning to go to a rock planning to go to a rock concert and plans to pay concert and plans to pay for two of his friend’s for two of his friend’s admission. admission.

Tickets are $36.50, how Tickets are $36.50, how much would Javier spend much would Javier spend on tickets?on tickets?

Answer: $109.50

Problem 4

Javier remembers that he has Javier remembers that he has to get a new tire for his car to get a new tire for his car before leaving, which costs before leaving, which costs $46.49. $46.49.

He also needs an oil change that He also needs an oil change that costs $17.95. costs $17.95.

He has a coupon for 25% off his He has a coupon for 25% off his total purchase. total purchase.

What is the total after the What is the total after the discount?discount?

Problem 5

Set it Up…Set it Up… The total cost is ________The total cost is ________

Answer: $48.33

If we take 25% off, we have 75% left… 100%-25% = 75%If we take 25% off, we have 75% left… 100%-25% = 75%

Try it two ways:Try it two ways: Find 25% of the total cost and subtract it from the total cost, orFind 25% of the total cost and subtract it from the total cost, or Take .75 (because we convert the % to a decimal) and multiply by the total cost!Take .75 (because we convert the % to a decimal) and multiply by the total cost!

$64.44$64.44