Download ENGLISH / MATH GRADE 6

ATENEO DE MANILA HIGH SCHOOL | TULONG-DUNONG TUTORING
MATH 6
LESSON GUIDE NO. 6
Division of Decimals
At the end of the session, the TD Kids should be able to
1. State the procedure for dividing decimals.
2. Divide decimals correctly
3. Solve simple word problems involving division of decimals.
REVIEW OF PREVIOUS LESSON / MOTIVATIONAL ACTIVITY FOR NEW LESSON
This part will be prepared by the TD tutors.
LESSON PROPER
A. Present the following word problem to the students:
Devi bought a length of ribbon that measured 14.7 m (meters). She needs to cut it into
strips of ribbon measuring 0.15 m long to make decorations for the Buwan ng Wika
Celebration in their school. She needs at least 90 strips of ribbon to complete her project.
Does she have enough ribbon for her project?
1. Ask the students to read the word problem out loud. Then instruct them to answer the
problem in their own notebooks.
2. After around 4 minutes, ask the kids to show their solutions and answers. (The correct
answer is that Devi has enough ribbon to complete her project. She only needs 90 small strips
of ribbon, but the long ribbon she has bought will yield 98 small strips.) Check if the students
were able to answer the problem correctly.
3. Point out that there are different ways of solving the word problem. One way is by
representing the word problem using an equation.
4. Demonstrate how to solve the above problem using an equation by going through the
following steps (based on Polya’s stages of problem-solving):
a) First, THINK about what is being asked and what operations are involved.
In the given word problem, what operation is involved? Since Devi needs to cut up a
length of ribbon into smaller pieces of uniform length, it involves division. To find out if
Devi has enough ribbon, she can divide the total length (14.7 m) by the length of each
small strip (0.15 m).
b) Next, PLAN how you can obtain the unknown by writing down an equation.
The problem can be represented as follows:
Let x = the number of small ribbon strips that can be produced from one long strip
The equation can be represented thus:
x =14.7¸ 0.15
c) After writing down the equation, SOLVE it:
x =14.7 ¸ 0.15
x = 98
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ATENEO DE MANILA HIGH SCHOOL | TULONG-DUNONG TUTORING
Another way to present the solution is as follows:
x
0.15 14.7
x
15 1470
x = 98
Since the long ribbon can produce 98 small strips, we can conclude that Devi has more
than enough ribbon for her project. (She only needs 90!)
d) Lastly, LOOK BACK and check if the answer is correct by using another method –
multiplication.
One other way to answer the problem is to simply multiply the number of small strips
Devi needs by 0.15 m. The product will be the exact length of ribbon she needs to
complete her project. If the product is less than 14.7 m, then we can conclude that
Devi has enough ribbon.
Let y = the total length of ribbon Devi needs for her project
y = 0.15´ 90
y = 13.5
13.5 < 14.7
Devi only needs a total of 13.5 m of ribbon to complete her project. Since she has
14.7m, we can conclude that she has more than enough ribbon for it.
B. Discuss the key ideas and processes involved in dividing decimals:
1. When dividing decimals, look first at the divisor. (The divisor is the number by which
another number is to be divided. In the above example, the divisor is 0.15.)
2. If the divisor is a whole number, then divide as you would whole numbers and place the
decimal point in the quotient in the same place as in the dividend.
3. If the divisor is a decimal, convert it to a whole number by multiplying it by the appropriate
power of 10 (moving the decimal point to the right to convert the divisor into a whole
number). Then, multiply the same amount to the dividend (moving the decimal point to the
right the same number of times as in the divisor). Use the new divisor and new dividend to
get the quotient.
4. Remember: if the quotient is a repeating, non-terminating decimal number, write it with a
bar on top of the repeating digits.
5. Give the following problem to illustrate the points discussed:
What is 10.25 divided by 0.5?
Let z = the quotient of the given dividend (10.25) and divisor (0.5)
z = 10.25 ¸ 0.5
z = 1025 ¸ 50
z = 20.5
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ATENEO DE MANILA HIGH SCHOOL | TULONG-DUNONG TUTORING
Points to Emphasize
A. No additional point is necessary for this lesson. However, it is important to check if the kids are
able to multiply fast and easily since basic multiplication is a prerequisite skill for this lesson.
B. If you have time, continue to practice the students in properly reading decimals (up to ten
thousandths). (You may give exercises where you read aloud a decimal while the students
represent what you read in numerical form.)
EXERCISES
A. Solve for N.
2.0 ¸ 6 = N
4.9 ¸ 0.3 = N
29.4 ¸1.4 = N
0.084 ¸ 0.24 = N
N
5. 1.25 27.55
1.
2.
3.
4.
6.
N
9 6
7. To be provided by the TD Kuya.
8. To be provided by the TD Kuya.
B. Fill in the missing numbers
1. 23.25¸1.5 = ____
2. 9.8¸ 0.5 = ____
3. 14.8¸ _____ = 7.4
4. 0.543¸ _____ = 0.03
5. To be provided by the TD Kuya.
6. To be provided by the TD Kuya.
C. Write an equation for each statement and then solve it.
1.
2.
3.
4.
0.402 divided by 2
c divided by 0.05 is 0.01
To be provided by the TD Kuya.
To be provided by the TD Kuya.
D. Solve the following word problems.
1. Mang Dionisio, the school janitor, receives Php 9, 880.50 for 20 days of work. How
much is his daily wage?
2. Mr Diviso would like to donate one of his estates measuring 10,438.92 square
meters (sq. m.) to St Mary Elementary School and 3 other charitable institutions. If
each institutions is to get an equal share, what is the size of the lot each one should
get?
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ATENEO DE MANILA HIGH SCHOOL | TULONG-DUNONG TUTORING
ENRICHMENT
[For Higher Horizons students] Help students practice the skill of estimating quotients. This skill
can come in handy when checking the final answer.
To estimate the quotient of two decimals, round off the divisor to the greatest nonzero place. Use
this whole number as the new divisor. Then take only the first digit of the quotient and add 0s
(zeroes) to hold the remaining places in the quotient.
For example, to estimate the quotient of 479 divided by 23.25, you may do the following:


First, round of the divisor (23.25) to the greatest nonzero place. In this case, to the nearest
tens place. Therefore, the divisor is simply 20.
When you divide 479 by 20, the first digit in the quotient is 2:
2_
20 479


Simply add a zero after 2 to hold the remaining place. The number thus becomes 20.
The estimated quotient 479 ÷ 23.25 is therefore 20.
EVALUATION
A. Solve for N.
1.
2.
3.
2.96 ¸ 0.8 = N
0.135¸1.5 = N
0.984 ¸ 0.12 = N
4.
N
013.2 7788
N
5. 0.32 0.448
B. Fill in the missing numbers
1. 11.22 ¸ _____ = 2.2
2. 11.3¸ 0.4 = ____
3. _____¸ 0.06 = 9.2
C. Write an equation for each statement and then solve it.
1. 8.6 is the quotient of x and 3
2. 23.3 divided by 2.5
D. Solve the following word problem.
During the long trip to the school from the house, Devi covered a total distance of
38.45 km (kilometers) in 1.25 hours. If Devi was going at constant speed, how
many kilometers did Devi cover per hour?
ASSIGNMENT
This part will be prepared by the TD tutors.
SOURCES
Sanchez et al. Essential Math Connections & Communication. QC: Dane Publishing House, Inc. 2004.
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