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.

Combination of Addition and Subtraction


Step II: Subtract 38 from the sum 79.

Combination of Addition and Subtraction

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.














Step II: Now, subtract 12 from 37.

37 - 12 = 25

Mixed Addition and Subtraction

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.

Add and Sub

Step II: Subtract the number with ‘-‘ sign from the sum of the numbers with ‘+’ sign.

Addition and Subtraction

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

Word Problem on Addition and Subtraction

Total number of cookies = 478 + 245 = 753

Cookies Distributed = 323


Step II: Subtraction

Word Problem on Addition and 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.

(i) 33 + 55 - 22

(ii) 58 + 31 - 64

Combination of Addition and Subtraction
Addition and Subtraction Together


(iii) 34 + 42 - 51


(iv) 46 + 21 - 15

Addition and Subtraction Together
Addition and Subtraction Together

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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