Combination of Addition and Subtraction
We will discuss here about the combination of addition and subtraction.
To show the problems involving both addition and subtraction, we first group all the numbers with ‘+’ and ‘-‘ signs. We find the sum of the numbers with ‘+’ sign and similarly the sum of all the numbers with ‘-‘ sign and then find the difference. If there is no sign before a number it means ‘+’ sign.
The rules which can be used to solve the sums involving addition (+) and subtraction (-) together are:
I: First add and then subtract,
II: Solve the numbers enclosed in the brackets and then solve further.
To solve the questions which involve both addition and subtraction, we first add and then subtract the required number from the sum.
1. 7 + 3 - 4 = ?
Step I: Add the numbers 5 and 3.
5 + 3 = 8
Step II: Subtract 4 from the sum we got in step I, that is 8.
48 - 4 = 4
Thus, 5 + 3 - 4 = 4
2. 56 + 23 - 38 = ?
Step I: Add the numbers 56 and 23.
Step II: Subtract 38 from the sum 79.
Thus, 56 + 23 - 38 = 41
3. Let us consider 11 + 26 - 12.
|
Step I: First add 11 and 26. The sum of 11 and 26 is 37.
37 - 12 = 25 |
Answer: 11 + 26 - 12 = 25
4. Let us take another example. A shopkeeper has 90 oranges. He sold 51 oranges on Monday and 25 oranges on Tuesday. How many oranges are left with him?
|
|
T O |
|
Oranges sold on Monday |
5 1 |
|
Oranges sold on Tuesday |
+ 2 5 |
|
Total oranges sold |
7 6 |
Oranges left = Total Oranges - Oranges Sold
|
|
T O |
|
Total Oranges |
9 0 |
|
Oranges Sold |
- 7 6 |
|
Number of Oranges Left |
1 4 |
Solved Example Involving Addition (+) and Subtraction (-) ogether:
1. Solve 3252 - 1802 + 2610
Solution:
3 2 5 2
+ 2 6 1 0
5 8 6 2
Now
5 8 6 2
- 1 8 0 2
4 0 6 0
2. Find the solution to (7259 - 5369) + 2156
Solution:
6 11 15
7 2 5 9
- 5 3 6 9
1 8 9 0
Now
1 1
1 8 9 0
+ 2 1 5 6
4 0 4 6
3. Subtract 4926 from the sum of 3051 and 4257
Solution:
Sum of 3051 and 4257
1
3 0 5 1
+ 4 2 5 7
7 3 0 8
Now, subtract 4926 from 7308
6 12 10
7 3 0 8
- 4 9 2 6
2 3 8 2
4. Solve 481 + 356 – 168.
Solution:
Step I: Add the numbers with ‘+’ sign.
Step II: Subtract the number with ‘-‘ sign from the sum of the numbers with ‘+’ sign.
Therefore, 481 + 356 – 168 = 669
Addition and Subtraction Together
5. 4235 - 4732 + 3543
|
Th H T O 4 2 3 5 + 3 5 4 3 7 7 7 8 |
Step I: First add 4235 + 3543 |
|
Th H T O 7 7 7 8 - 4 7 3 2 3 4 4 6 |
Step II: Subtract 4732 from result of step I i.e., 7778 |
Remember:
● If there is no +/- sign before numbers then always assume + sign.
● First add and then subtract the digit.
● Subtract the digits which face '-' sign.
Word Problems on Addition and Subtraction Together:
6. Neel's mother baked 4 cookies. When Sam joined in, she baked 7 more cookies. Neel and Sam ate up 9 cookies. How many cookies were left?
Neel's mother first baked 4 cookies
Then, she baked (+) 7 more cookies
There were 1 1 cookies in all
Neel and Sam ate (-) 9 cookies
There were 2 cookies left
Thus, 2 cookies were left.
7. Surbhi had 24 stamps. She got 50 more from her aunt. She gave 40 to a friend. How many does she have now?
Solution:
Surbhi had 24 stamps
She got (+) 50 more
There were 74 stamps
She gave (-) 40 stamps
There were 34 stamps left
Thus, Surbhi is left with 34 stamps.
8. Daniel has 478 chocolate cookies and 245 chocolate chip cookies. He distributed 323 cookies among his friends. How many cookies were left with him?
Solution:
Chocolate cookies = 478
Chocolate chip cookies = 245
Step I: Addition
Total number of cookies = 478 + 245 = 753
Cookies Distributed = 323
Step II: Subtraction
Cookies left with Daniel = 753 - 323 = 430
Questions and Answers on Addition and Subtraction Together:
1. Add and subtract the following 1-digit numbers.
(i) 8 + 1 - 6
Step I: 8 + 1 = ___
Step II: ___ - 6 = ___
Thus, 8 + 1 - 6 = ___ - 6 = ___
(ii) 7 + 3 - 2
Step I: 7 + 3 = ___
Step II: ___ - 2 = ___
Thus, 7 + 3 - 2 = ___ - 2 = ___
2. Add and subtract the following 2-digit numbers.
Answer:
2. (i) 66
(ii) 25
(iii) 25
(iv) 52
3. Fill in the blanks -
(i) 5555 - 3213 + 4235
|
Th H T O 5 5 5 5 + 4 2 3 5
|
Th H T O _ _ _ _ - 3 2 1 3
|
(ii) 5362 - 4141 + 2222
|
Th H T O 5 3 6 2 + 2 2 2 2
|
Th H T O _ _ _ _ -
|
(iii) 6247 + 2431 - 5132
|
Th H T O 6 2 4 7 + 2 4 3 1
|
Th H T O _ _ _ _ - 5 1 3 2
|
(iv) 4321 + 1541 - 3323
|
Th H T O 4 3 2 1 + 1 5 4 1
|
Th H T O _ _ _ _ -
|
Answer:
3. (i)
|
Th H T O 5 5 5 5 + 4 2 3 5 9 7 9 0 |
Th H T O 9 7 9 0 - 3 2 1 3 6 5 7 7 |
(ii)
|
Th H T O 5 3 6 2 + 2 2 2 2 7 5 8 4 |
Th H T O 7 5 8 4 - 4 1 4 1 3 4 4 3 |
(iii)
|
Th H T O 6 2 4 7 + 2 4 3 1 8 6 7 8 |
Th H T O 8 6 7 8 - 5 1 3 2 3 5 4 6 |
(iv)
|
Th H T O 4 3 2 1 + 1 5 4 1 5 8 6 2 |
Th H T O 5 8 6 2 - 3 3 2 3 2 5 3 9 |
4. Do these sums in your notebook -
(i) 2222 + 3333 - 1111
(ii) 3122 + 4212 - 2112
(iii) 4364 + 3213 - 6243
(iv) 5154 + 2343 - 4265
(v) 8546 - 6324 - 2112
(vi) 9798 - 7656 + 7554
(vii) 8746 - 5534 + 2465
(viii) 3778 - 2563 + 4672
(ix) 2432 + 1342 - 1121
(x) 4365 + 434 - 1213
(xi) 3794 + 1213 - 2505
(xii) 7811 - 1222 + 234
(xiii) 5234 + 3259 - 4172
(xiv) 3777 + 2111 - 4352
(xv) 2725 + 1234 - 786
(xvi) 2575 + 2430 - 1225
(xvii) 7250 - 5450 + 3550
(xviii) 2775 + 1465 - 1275
(xix) 2537 - 2425 + 1212
(xx) 4533 - 2322 + 289
Answer:
4. (i) 4444
(ii) 5222
(iii) 1334
(iv) 3232
(v) 110
(vi) 9696
(vii) 5677
(viii) 5887
(ix) 2653
(x) 3586
(xi) 2502
(xii) 6823
(xiii) 4321
(xiv) 1536
(xv) 3173
(xvi) 3780
(xvii) 5350
(xviii) 2965
(xix) 1324
(xx) 2500
Word Problems on Combination of Addition and Subtraction:
5. 3 swans are swimming in a lake. 4 more swans join in. Then 5 swans fly away. How many swans remain?
Answer: 2
6. Renu has 23 black pencils and 14 purple pencils. She cannot use 9 pencils as their tips are broken. How many pencils does Renu have that are not broken?
Answer: 28
7. Rohan put 54 coins in his piggy bank. Later, he put 33 more coins in the piggy bank. Then he took out 60 coins. How many coins are left in his piggy bank?
Answer: 27
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