N4 Numbers : Addition and Subtraction

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ADDITION

~ bringing two or more numbers (parts) together to make a new total (whole).

              

          1 apple ADD TO 2 apples is equal to 3 apples    

                          1           +                2               =        3

                PART       +            PART           = WHOLE

       

                        2 + 1 is the same as 1 + 2 equals 3

Doing Addition Word Problems

Method

Step1:        [Know the story, and underline] Who and what in the game?

Step2:        [Plan the solution and double underline] What is needed? altogether 

Step3:        [Do] How to win?

Example

Judy has 3 books. Annie has 5 books. How many books do the girls have altogether?

Step1: Know the story and Underline

              Judy part: 3

            Annie Part: 5

Step2: Plan needed: how many books altogether [double underline]

Altogether -> total, the whole -> ADD

Step3: Do

-> Add the parts to find the whole

            3 + 5 = 8

The girls have 8 books altogether.

Example

There are 4 pears and 2 oranges in a basket. Kenny puts 5 apples into the basket. How many fruits are there in the basket altogether?

Step1: [Know the story and underline] Who and what? 

        Pears and oranges are fruits, In the basket

               pear : 4

            orange: 2

       Apple is also fruit. Put 5 apples in basket

Step2: [Plan]. What is Required: fruits altogether (double underline)

       Altogether -> total, the whole -> ADD

Step3: [Do]

      -> Add the parts to find the whole

            4 + 2 + 5 = 11

There are 11 fruits in the basket.

SUBTRACTION

~ an operation to remove objects from a collection.

~ take away(something) from something else to decrease the number or amount

        

            To find one part, we subtract the other part from the whole

                        3 - 1 is the same as 2. 3 minus 1 equals 2

Example

Jana has 12 cookies. She ate 5 cookies . How many cookies does Jana have?

Method

Step1: [Know the story and underline] Who and what? 

            Jana : has 12 

                        ate    5

Step2: [Plan]. What is Required: left (double underline)

        left ->  subtract

Step3: [Do]

        -> 12 - 5

            12 – 5 = 7

There are 7 cookies left.

Example (add / subtract)

There were 15 passengers in the MRT cabin at first. At the next stop, 7 passengers entered the cabin and 9 passengers left. How many passengers are in the MRT cabin now?

Method

Step1: [Know the story and underline] Who and what? 

            passenger:   15  

                                     7 enter -> (more passengers)

                                      9 left -> (less passengers)

Step2: [Plan]. What is Required: in cabin now (double underline)

            enter -> add

            left ->  subtract

Step3: [Do]

             15 + 7 = 22

              22 – 9 = 13

There are 13 passengers in cabin.

Example (add/subtract)

Annie, Jen and Linda each has 8 balloons. Jen and Linda’s balloon burst and Jen has 4 balloons less than Linda. Annie has 2 balloons more than Linda. How many balloons do Jen and Linda have?

Method

Step1: [Know the story and underline] Who and what? 

   Annie   : 8 

    Jen     : 8 -

    Linda  : 8 - 

   Jen, Linda burst -> lesser. Annie has the most.

     Annie 2 balloons more than Linda  

Step2: [Plan]. What is Required: Jen and Linda ballons (double underline)

     Annie 2 balloons more than Linda , Annie has 8 balloons

             ->  Annie – Linda 

            Jen has 4 balloons less than Linda 

            -> Linda - Jen

Step3: [Do]

             Linda : 8 – 2 = 6

            Jen : 6 – 4 = 2

    ~~~~ END ~~~~ :)