Number Operations in Grade IV

Hello friends our today’s topic is the most basic topic of mathematics. In today’s session we will learn numbers, operations. Specifically addition and subtraction. When we start learning math, our faculty first introduces us with the numbers. Numbers (also read what are prime numbers) are the base of math. Numbers in mathematics are 0, 1, 2, 3, 4…. N.

Operations can be defined as the manipulation performed on numbers. There are four basic operations which are Addition, Subtraction, Multiplication, Division

In today’s topic we will only discuss Addition and Subtraction. So we will start with the Addition first.

Addition is the operation to total something. Here by total we mean to join two or more numbers (also read rational numbers worksheet). Symbol + is used to denote the operation of addition.

Example:

Suppose we have two numbers “A” and “B” and “R” is the total after the addition operation. So the Addition operation is defined as:

                        A + B = R

And in words “ A plus B equals to R ”.

Now putting numbers in place of  A, B and R.

We will start with the simplest one.

Single digit addition:

                                    1 + 1 = 2

                                    3 + 5 = 5 + 3 = 8

                                    4 + 3 = 3 + 4 = 7

Have you noticed something in above examples. No! If we change the order of number then the result will not be affected. It will remain the same.          

Two digits addition

                                    10 + 3 = 13

                                    25 + 24 = 49

                                    60 + 20 = 80

Similarly we can add “n” digit numbers.

By following the process below

Step 1: arrange the digits of the number in column form.

Step 2: Now add it as the single digit number starting from right to left. And if carry is generated then count it on the column left to it and put the result in the last row.

Example:

                        Add 123+345+789

               1 2 3

            +  3 4 5

            +  7 8 9

        -------------------

             1 2 5 7

Subtraction is the operation to taking something. Symbol minus (–) is used to denote the operation of subtraction.

Example:

Suppose we have two numbers “A” and “B” and “R” is the result after the subtraction operation. So the subtraction operation is defined as:

                        A - B = R

And in words “ A minus B equals to R ”.

Now putting numbers in place of A, B and R.

We will start with the simplest one.

Single digit subtraction:

                                    4 - 1 = 3 but 1 – 4 = -3

                                    5 - 3 = 2 but 3 – 5 = -2

                                    4 - 3 = 1 but 3 – 4 = -1

Have you noticed something in above examples. No! If we change the order of number then the result will be changed too. That is the order of numbers are important.

Two digits subtraction:

                                    10 - 3 = 7

                                    25 - 24= 1

                                    60 - 20 = 40

Similarly we can subtract “n” digit numbers.

By following the process below:

Step 1: arrange the digits of the number in column form.

Step 2: Now subtract it as the single digit number starting from right to left. If the above number is smaller then the number down then take borrow from the number in left column.

Example:

            Subtract 987-342

              9 8 7

            - 3 4 2

          -------------

              6 4 5 

Isn't it very easy. It will take no time to get master. Just spent some little time and you will be perfect in it.

In upcoming posts we will discuss about Positive Numbers in Grade IV and Mathematical Reasoning. Visit our website for information on ICSE syllabus for business studies