Confidential 1

Dividing Decimals

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WARM – UP

1. 25.60 X 1.007 = 25.7792

2. The number 0.8 times 0.8 equals 0.64

3. 9.59 x 0.001 = 0.00959

4. Place a decimal point in the product

8.5 x 17.2 = 146.2

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Lets review what we did in the last lesson

To multiply we first ignore the decimals and multiply as usual as you do with whole numbers

Now add the products

To place the decimal points point in the answer we start from the right and move the number of places equal to the sum of the decimal places in both the numbers multiplied

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Lets find the product of

0.2 x 6.5

Multiply as usual ignoring the decimal points

2 x 65 = 130

Now in the product start from the right and move left 2 places ,then place the decimal

We get 0.2 x 6.5 = 1.30

Lets try an Example

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Lets get started

Steps for dividing by whole numbers 1) If the division problem is written across, copy the

problem so that the first number is inside the division sign. If the problem is 35.2 ÷ 5 then write it as

5) 35.2

2) Place decimal point in the quotient directly above the decimal point in the dividend.

3) Now use the long division method as if there were

no decimal points involved.

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Steps for division by whole number

)

35.2535 0 2 0 2 0 0

7 .04 0 If the number left

is smaller than the number outside add a zero in thequotient and in the end of the inside number

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Steps for dividing by decimal numbers

Write the first number inside the division sign

Change the divisor to a whole number by moving the

decimal point to the right Move the decimal point of the inside number

( dividend) the same number of places to the right as you did

of the divisor.

Put the decimal point for your answer directly above the one in your inside number.

Divide the same way as you do with whole numbers

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3.33 ) 2 2.1 7 7 8

Lets take an Example

Move the decimal point of the inside number (dividend) the same number of places to the right as you did of the divisor. So we get…

Change the divisor to a whole number by moving the decimal point to the right

333 ) 2 2 1 7. 7 8

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333 ) 2 2 1 7. 7 8

Place a decimal point on top of the decimal point of the inside number and divide normally

.6

1 9 9 8

2 1 9 7

6 6

1 9 9 8

1 9 9 81 9 9 8

0

= Answer

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Re write the following questions after placing thedecimals in correct places

15.5 ÷ 0.00515500 ÷ 5

347.887 ÷ 0.6734788.7 ÷ 67

34.23 ÷ 0.00534230 ÷ 5

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Lets take another Example

0.452 ÷ 0.5

.5 ) .452 45 2 0 2 0 0

0 0.904

If there is a remainder then add zero to the inside number.

Bring them down and divide until there is no reminder or until there are 4 decimal places in your answer

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You can also check your answer by multiplying the quotient with the divisor . If it is same as the dividend then your answer is correct

0.5 x 0.904 = 0.452

.

0.452 ÷ 0.5 = 0.904

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Lets try another Example with negative numbers

-31.48 ÷ -4

-4 ) -3 1 .48 - 28 3 4 3 2 2 8 2 8 0

7 . 87

When we divide two numbers

With the same sign we get + and with different signs

we get -

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Now you try some!

1)89.45 ÷ 0.908 = 98.5132

2) 0.5194 ÷ 0.49 = 1.06

3)0.0528 ÷ 0.06 = 0.88

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BREAK TIME

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Click on the photo to play the game

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One rectangle has an area of 2.04 sq. meters , and a second has an area of 1.86 sq. meters. If the length of both rectangles is 0.6 meter. Which rectangle is wider ? Explain

The first rectangle ; you would divide 2.04 by 0.6 and 1.86 by 0.6 to find the widths. The divisors are same ,

so 2.04 / 0.6 will be greater than 1.86 / 0.6

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Susie earns $10,000 in a year. She bought a bike worth $3000 and paid only $1000 upfront. The remaining money she has to pay as EMI. If she can only spare 10% of her monthly salary as EMI. Calculate in how many months will she pay off her loan?

Monthly Salary 10,000 ÷ 12 = $833.34

10% of 833.34 = 83.33

Loan is $2000 EMI is $83.33

Number of Months required = 2000 ÷ 83.33 = 24 Months

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A Ping – Pong table has an area of 4.165 sq. meters, while a tennis court has an area of 260.76 sq. meters. To the nearest hundredth, how many times larger is the tennis court than the Ping –Pong table ?

62.61 times

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Assessment

1. Find each quotient:a) 9.12 ÷ 6 = 1.52

b) 385.6 ÷ 8 = 48.2

c) 1.728 ÷ 12= 0.144

2. Find each quotient:a) 0.248 ÷ 0.04= 6.2

b) 8.64 ÷ 0.08=108

c) 38.125 ÷ 1.25=30.5

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Assessment

3. There are 45 students waiting in line to take a tram car to the top of a mountain. Each car can take only 6 people at a time. How many cars will be needed to carry all the students? 8 tram cars

4. A chemist is mixing different solutions. If 90 milliliters of a solution need to be divided equally into 8 test tubes, how much should go into each test tube? Does the answer need to be exact or could the chemist use an estimate? Explain your answer.11.25 mL. Sample answer: Exact; the experiment may not work if one has too much or too little

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Assessment

5. Find the gas mileage: A family car travels 367.9 miles on 12.5 gallons of gas. Round to the nearest tenth. (29.4mi/gal)

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Review

To divide two decimal numbers , change the divisor to a whole number by moving the decimal point to the right Then move the decimal point in the dividend the same number of places to the right

Then divide as with whole numbers

In the answer put the decimal point just above the decimal point in the dividend.If there is a remainder, add zero to the dividend and divide until there is no remainder or until there are four decimal places in the quotient

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Review

96) 1996.8 192 76 8 76 8 0

20.8

Find 199.68 ÷ 9.6

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You had a Great Lesson Today

Be sure to practice what you have learned today