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Lesson 9
PROBLEM SOLVING INVOLVING SUBTRACTION
Objectives
After this lesson, the students are expected to:
follow the steps correctly in problem solving involving subtraction;
discuss the different steps in problem solving; develop the knowledge in problem solving.
Pedro had marbles. He gave away two of his marbles to Juan. If Pedro had twelve
marbles, how many marbles left to Pedro after he gave two to Juan?
We can use the problem solving plan:
1. Know what the problem is.
a. What is asked? How many marbles left to Pedro?
b. What are given? 12 marbles of Pedro and 2 to Juan
c. What operation to be used? Subtraction
To master the application of subtraction in problem solving, here are some examples:
12 – 2 = n 12 – 2 = 10
N = 10 marbles left to Pedro.
Checking:
2 + 10 = n 2 + 10 = 12
Another example:
Mt. Everest, is 29 028 ft. high, while the Mt. McKinley is 20 320 ft. high. How much
is Mt. Everest higher than Mt. McKinley?
1. What is asked?
How much Mt. Everest higher than Mt. McKinley?
2. What are given?
Mt. Everest, is 29 028 ft. high and Mt. McKinley is 20 320 ft. high.
3. What operation to be used?
Subtraction
29 028 – 20 320 = n
29 028 – 20 320 = 8 708 ft.
Checking:
8 708 + 20 320 = n
8 708 + 20 320 = 29 028
WORKSHEET NO. 9
NAME: ___________________________________ DATE: _____________
YEAR & SECTION: ________________________ RATING: ___________
1. In 1992, William Clinton got 44 908 254 votes as the president of USA while George
Bush got 39 10 343 votes and Foss Perot got 19 741 65 votes. How many more votes
did Clinton have than Bush? Bush than Foss?
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2. In May of 1994, there were 42 518 000 beneficiaries in the social security program
while there were 41 784 000 beneficiaries on May 1993. How much was the increase
of beneficiaries from 1993 to 1994?
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________________________________________________________________________
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___________________________________________________________.
A. Get one whole sheet of paper and
solve the following problem.
3. In 1998, a school had an enrollment of 5908 pupils while there are 6519 pupils
enrolled in 1999. How much more pupils enrolled in 1999 than in 1998?
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4. Martial law was declared in 1972. Now, it is 2009, how many years ago it was?
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5. If Clark was born on December 31 2009, how old is he now?
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6. What number will make 2 816 to become 5229?
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7. A philanthropist donated P850 765 to an orphanage. The amount was used for some
repairs and the purchase of some equipment worth P519 800. How much money was
left for other projects?
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8. If you born on 1953, how old are you now?
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9. Mr. Fabre exported to other Asian countries P2 759 000 worth of furniture while Mr.
Co exported P5 016 298 worth. How much more where Mr. Co’s exports than those
of Mr. Fabre?
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10. The total number of eggs produced in the United States in 1993 was 71, 391,
000,000. The total number of eggs produced in 1992 was 70,541,000,000. How
many more eggs were produced in the United States in 1993 than in 1992?
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