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Page 25: Chapter 3 Warm-Up
Afsana is solving a path puzzle. Help her find the missing numbers.
Number path
2
_
5
_
25
_
35
_
Remember
Count forward and backward carefully. The printed page number in the book is 25.
Addition and Subtraction
Study
17 pages
Addition and Subtraction
Let's build and break! Chapter 3 uses columns, number lines, abacus, and word problems to add and subtract numbers up to 999.
What you'll learn
Main skills from this lesson
Add and subtract numbers in different ways
Use column method, number line, and abacus
Solve word problems in daily life
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Page 26: Using Column Method
Addition
Namra had 145 seashells and Saima had 159 seashells. Add them using columns.
| Hundreds | Tens | Ones | |
|---|---|---|---|
| 145 | 1 | 4 | 5 |
| 159 | 1 | 5 | 9 |
| 304 | 3 | 0 | 4 |
Remember
Start from the ones column, regroup the tens, then add the hundreds.
Practice
5 ones + 9 ones =?
14 ones
14 ones =?
1 ten + 4 ones
1 hundred + 1 hundred + 1 carry =?
3 hundreds
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Page 27: Subtracting with Regrouping
Shafraz had 242 stickers and gave away 158 stickers. Work out how many are left.
| Hundreds | Tens | Ones | |
|---|---|---|---|
| 242 | 2 | 4 | 2 |
| 158 | 1 | 5 | 8 |
| 84 | 0 | 8 | 4 |
Remember
When the ones are not enough, regroup the tens. Then regroup the hundreds if needed.
Practice
2 ones minus 8 ones needs regrouping from which column?
Tens
5 tens minus 5 tens gives how many tens?
0 tens
2 hundreds minus 1 hundred gives how many hundreds?
1 hundred
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Page 28: Using Abacus
Use the abacus to solve bigger addition and subtraction facts. Make your own problems and discuss them with a partner.
235
Hundreds-Tens-Ones
2
Tens
3
Ones
142
Another example
1
Tens
4
Ones
Remember
The printed book asks children to make and discuss their own facts too.
Practice
If you add 235 and 135, what do you get?
370
If you subtract 423 and 142, what is left?
281
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Page 29: Exercise 1
Rihaan and Nasru are playing with number cards. They want to make combinations of 100.
Add or subtract the given numbers as indicated.
Workbook
a. 242 - 112
Answer: 1, 3, 0
b. 342 + 126
Answer: 4, 6, 8
c. 237 - 109
Answer: 1, 2, 8
d. 261 + 451
Answer: 7, 1, 2
Remember
Use the table and a strategy of your choice. Keep the columns straight.
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Page 30: Exercise 1 Continued
Solve the questions in the locks and keys. 4. Make any 4 addition and subtraction facts using the given number cards.
250, 150, 100, +, -
Remember
Find the matching pairs and then build your own facts with the number cards.
Practice
345 + 236
581
765 - 499
266
702 - 208
494
119 + 301
420
689 - 496
193
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Page 31: Splitting Strategy
Look at how Sameer and Zoya use two different ways to solve the same problem.
Split the numbers into hundreds, tens and ones, then add or subtract each part.
234 + 125 = 359 565 - 234 = 331
Remember
One method splits both numbers. The other method changes the second number one part at a time.
Practice
234 + 125 by splitting gives?
359
565 - 234 by splitting gives?
331
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Page 8
Page 32: Using Number Line
Use a number line to jump forward for addition and backwards for subtraction.
Number path
239
_
_
339
349
359
_
_
364
Remember
Count by hundreds, tens, and ones to reach the answer.
Practice
From 239, jump forward by 100. Where do you land?
339
From 635, jump back by 233. What is the result?
402
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Page 33: Compensation Strategy
D. Compensation Strategy
In compensation strategy, we can think flexibly about numbers. Look at the given example.
Suleiman solved the same problem using another strategy.
We can also use compensation strategy for subtraction.
238 + 425 = 663 304 + 267 = 571 664 - 395 = 269
Remember
Sometimes, we first add or subtract a friendly number and then compensate to get the answer.
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Page 34: Exercise 2
Solve the following. You may use a strategy of your choice.
Add the following numbers.
Remember
Mix and match the strategy that feels easiest. Keep the columns aligned and check your answer before moving on.
Practice
252 + 147
399
679 - 534
145
165 + 333
498
415 - 312
103
428 + 221
649
356 - 124
232
328 + 205
533
347 + 297
644
206 + 419
625
399 - 206
193
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Page 35: Addition and Subtraction in Daily Life
A baker made cookies, sold some, and asked how many were left. Use the table and talk about the steps with a friend.
| Chocolate cookies | Coconut cookies | Number sold | Number left |
|---|---|---|---|
| 200 | 150 | 215 | ? |
Remember
To solve word problems: understand the problem, make a plan, solve it, and check again.
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Page 36: Exercise 3
Solve the following word problems.
Remember
Read each story carefully. Find the numbers you need before you calculate.
Practice
156 pages in a book. Zaisha read 56 pages on Monday and 34 pages on Tuesday. How many pages are still left?
66
Aboobakuru has 130 apples and 125 mangoes. He sold 135 fruits in total. How many fruits were left unsold?
120
Farida bought 200 stickers, used 134, then Ismat used 58 from the remaining ones. How many stickers are left?
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Gazala had 145 in her money bank, received 200, then used 118. How much money is left?
227
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Page 37: Exercise 3 Continued
Make word problems using the given hints.
Look at the mountain peaks and answer the questions.
A, B, C, D, E mountains with heights 650 m, 827 m, 721 m, 937 m, 850 m
Remember
Use the clues to compare the heights and talk about the difference.
Practice
475 + 275
750
421 - 200
221
250 -? = 200
50
Which peak is the tallest?
Peak D
Which peak is the shortest?
Peak A
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Page 38: Vocabulary and Thinking Cap
Vocabulary: borrowing, consecutive, breaking up, regrouping, carry over, splitting strategy.
Put your thinking cap on! 10 more than my number is the same as 100 less than 320.
Remember
Explain the strategy you used and talk about your answer with a friend.
Practice
What is my number?
210
Write a similar number puzzle of your own.
Open answer
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Page 39: Mixed Practice
Yamin dropped ink on his notebook. Circle the correct answers in the column grids. Then solve the bar-model question.
H T O puzzle grids and bar model
Remember
Use the clues to find the hidden digits and complete the bar model.
Practice
131 + 326 =?
457
243 + 416 =?
659
260 + 59 =?
319
740 - 333 =?
407
What is 50 + 150?
200
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Page 40: What Do You Know?
Solve the puzzle and colour the parts with the correct answers.
Remember
Check each result carefully. The finished picture is the reward.
Practice
345 + 543
888
740 - 333
407
580 + 406
986
529 + 382
911
765 - 567
198
999 - 188
811
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Page 41: Mountain Peaks
Look at the mountain peaks and answer the questions about height.
A 650 m | B 827 m | C 721 m | D 937 m | E 850 m
Remember
Compare the heights and use subtraction to find the differences.
Practice
Which peak is tallest?
D
Which peaks are higher than 700 m?
B, C, D, E
Which peak is shortest?
A
Difference between highest and lowest peak?
287 m
How much taller is D than C?
216 m
How much shorter is A than B?
177 m
Great work
Continue with quizzes, flashcards, or games when you are ready.