# e - P ages 3 Jenny's Homework Subtracting Across Zero

```Vol. 10 No. 2 SY 2004-2005 ISSN 0118-2595
Jenny’s
Homework
Bird’s Nests
Subtracting
Across Zero
Articles
• Price Chart
3
e-Pages
JENNY’S HOMEWORK
By Dr. Alice C. Raganas
W
hile on their way home from school, Jenny was
telling her parents about their lesson in Math.
“My teacher taught us the Roman numerals and their
corresponding Hindu-Arabic numbers. The ancient Romans
used the letters I, V, X, L, C, D, and M to form numerals.
These Roman numerals have a value of 1, 5, 10, 50, 100,
500, and 1 000, respectively. She also taught us how to
read Roman numerals. We read Roman numerals from left
to right. She also mentioned some rules we must follow
when we use Roman numerals. For our assignment, she
asked us to list down the places where we usually see the
Roman numerals,” explained Jenny.
Her father slowly stopped the car. “Look at that building. What can
you see?” Mr. Dalen pointed to the top of the building.
“It says MDCCLIX, and it means 1759, Dad. What does
it mean?”
“It means that this building was built in the year 1759,”
her father replied.
“By the way, I have here with me a book. Look at the
chapter page. How does the number of each chapter written
in this book?” asked Mrs. Dalen.
“It says Chapter XXVI, meaning Chapter 26,” replied Jenny.
“How about the book copyright date? How was it written?” her
“The book says, MCMLXXXIV meaning 1984,” replied Jenny.
At home, father got a CD. “Come, Jenny, let’s watch this CD,” Mr.
Dalen invited Jenny, showing the CD to her.
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After a few minutes, Mr. Dalen paused the movie. “The movie
copyright date was MCMXCV, which means that this movie was
copyrighted in the year 1995,” he explained brieﬂy.
“Dad, do you mean we also use Roman numbers in this movie?” the
“Yes, you are right. You know that the main character of the movie
was King Richard III. We also use Roman numerals in writing names of
persons,” her father added.
“Now, I have answers to our homework. Roman numbers are used in
writing the following:
1.
Chapter number of a book
2.
3.
Name of a person
4.
Date on building
5.
“Thanks, Dad,” said Jenny.
“You’re welcome, Jenny.”
Try This
Write each of the following as a standard numeral.
1. Chapter of a book
XVI
__________
2. Book copyright date
MCMXCVIII
__________
3. King Philip
II
__________
4. Date on Building
MCMLXXXIX
__________
5. Movie copyright date
MMIV
__________
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BIRD’S NESTS
By Dr. Alice C. Raganas
L
ilibeth and Sarah lived in the province. Last summer, the two
friends volunteered to help a scientist keep track of bird’s nests.
They had been doing this for two years already. As volunteers, they
were always on the lookout for bird’s nests. As early as dawn until
sunset, they would start searching for nests.
Every day, they would wake up early to do their chores. Lilibeth
prepared breakfast, while Sarah prepared the materials needed for their
hike to the mountains and forests.
One day, after having their lunch, Sarah told Lilibeth that she
found 4 380 nests last year.
“I found 6 645 nests last year,” said Lilibeth.
“What if we will combine the number of nests we found in one
year, how many nests have we found all together?” asked Lilibeth.
The two friends made a computation:
Sarah’s way
4 380
+ 6 645
11 025
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Lilibeth’s way
First 1 estimated.
4 000 + 7 000 = 11 000
Then I used a calculator.
4 380 + 6 645 = 11 025
11 025 is close to 11 000
So, we have found 11 025 bird’s nests.
“Why did you estimate before you used the calculator?” asked Sarah.
“I estimated ﬁrst to decide if the sum of 4 380 and 6 645 is more or less
than 11 000,” replied Lilibeth.
Try This
1. Find the sum of 937 and 4 619.
2. Estimate to decide if the sum of 9 637 + 2 935 is greater than or
less than 13 000.
3. Who found the most bird’s nests — Sarah or Lilibeth? Explain
how did you know.
4. How much more bird’s nests did Lilibeth ﬁnd than Sarah?
5. Both women search for nests between 8 to 12 hours a day. If
Lilibeth begins searching at 8:15 a.m., what time will it be 10
hours later?
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SUBTRACTING
ACROSS ZERO
By Dr. Alice C. Raganas
I
n her Math class, Ms. Gonzales tells two students to ﬁnd the
difference between 206 and 129. Alvin and Pamela stand up to
solve the equation on the blackboard. After a few more minutes,
the two students have ﬁnished the task almost at the same time.
“Look at Alvin’s work and at Pamela’s work. Do you have
any comment?” Ms. Gonzales asks the class.
The pupils are silent. Everybody’s attention is on the solutions
that Alvin and Pamela did.
Alvin’s way
Pamela’s way
9
1 10 16
1 9 16
206
–129
77
206
–129
77
After awhile, Ms. Gonzales calls up Alvin and Pamela to
explain how each of them got their answer.
Alvin explains his answer ﬁrst. “Since there are no tens, I’ll
regroup the hundreds. Then, I can regroup the tens. Now, I can
subtract the ones,” Alvin explains conﬁdently.
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“Two hundreds is 20 tens,” Pamela said. “One less ten is 10 more
ones. I’ll add to check. 77 + 129 = 206. The answer is correct,” Pamela
Try This
A. Subtract. Check each answer.
1.
405
– 91
2.
605
– 496
3.
700
– 33
4.
405
– 257
5.
406
– 138
6.
905
– 296
7.
603
– 357
8.
704
– 635
9.
610
– 238
10.
307
– 89
B. Answer the following questions.
1. What is 602 minus 316?
2. What is the difference between 300 and 158?
3. What number could you subtract from 301 without regrouping.
What is the difference?
4. Ms. Uy bought a new lampshade for P 789. She paid for it with a
P1 000.00. How much change did she get?
5. Some students need to wash 100 cars to raise money for a school
trip. They have washed 56 cars. About how many more cars do
they need to wash?
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Answers to “Try This”
Jenny’s Homework
1.
2.
3.
4.
5.
16
1998
2
1989
2004
Bird’s Nests
1.
2.
3.
4.
5.
5556
10 000 + 3 000 = 13 000
Lilibeth 6645 &gt; 4380
2265 bird’s nests
6:15 p.m.
Subtracting Across Zero
A. 1. 314
2. 109
3. 667
4. 148
5. 268
6. 609
7. 246
8. 69
9. 372
10. 218
B. 1.
2.
3.
4.
5.
286
142
300, 1
P211.00
44 cars
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