Operations on Numbers
Addition
To find total or count the objects together we use addition.
Example:
If we have some fruits in two baskets. We put them all together in one big basket. Now to find the total number of fruits, we need to do an Addition.
- For the sentences ‘all together’, ‘total number’, ‘how many in all’, etc., we need to do addition.
- Addition is represented by the symbol ‘+’ read as ‘plus’.
Example :
Addition of the numbers 3 and 4 is written as: ‘3+4’.
It is read as ‘3 plus 4’.
Representation:
- We can add numbers by writing them horizontally as well as vertically in columns.
- The numbers that are added together are called Addends.
- When we add two or more numbers, the result is called the Sum. For example;
- The symbol ‘=’ is read as ‘is equal to’.
- ‘4 + 5 = 9’ is read as 4 plus 5 is equal to 9.
Addition of single digit numbers
We can add two numbers in so many ways.
1. By using fingers
We can use our hand’s fingers to do the addition. Let’s see.
Nisha has three chocolates. Bipin gives her two more chocolates. Now, we have to find the total number of chocolates Nisha has.
First method:
For three chocolates open three fingers of one hand.
For two chocolates open two more fingers of the other hand.
Now count all the fingers together.
We get the number 5.
So, Nisha has 5 chocolates in total now.
Second method:
For adding 3 and 2, open only two fingers of the hand and count after the number 3.
It will also give the same answer.
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2. By using counters
Counters: Each counter (object or shape) represent a number.
For example:
6+3= ?
Here we can take any object or shape to represent the numbers.
(Counter)
For the number 6 draw six circles.
For the number 3, draw 3 more circles.
Now, count all the circles together.
There are 9 circles in total.
So, we came to know that,
6+3= 9
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3. By using a number line
Number line: A straight line on which numbers are placed at the same distance and in the correct order. Numbers are placed from left to right.
By using number line, we can easily make an addition.
For example:
2+6= ?
First on a number line mark the number 2.
Now move six steps forward to the right side and observe the number where we reach.
We reach at the number 8.
So, 8 is the sum of 2 and 6.
2+6= 8
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4. Do Mentally
By counting mentally, we can do addition.
For example:
4+3= ?
Now, let’s think about the number 4 and count 3 more numbers after 4.
We get the number 7.
So, the sum of the numbers 4 and 3 is equal to 7.
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Facts
1. When we add 0 to a number, the answer is the number itself.
Example:
1+0=1
6+0=6
0+8=8
0+9=9
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2. When we add 1 to a number, the answer is the next number.
Example:
1. 2+1=3
Counting the one step forward to 2, we get the number 3.
Finding missing numerals in addition:
Example:
Here we can take any two numbers whose sum is 5.
0 + 5 = 5
1 + 4 = 5
2 + 3 = 5
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Word problems:
We can solve word problems based on addition by the following steps
Step 1: Identify the numbers in the word problem which need to be added.
Step 2: Write the word problem in the form of addition.
Step 3: Do the addition to find the sum.
Example:
Question: There are 3 red balls and 6 green balls in a box. How many total balls are there in the box?
Answer: Since there are 3 red balls and 6 green balls in the box, we need to add 3 and 6 to find the total number of balls in the box.
There is total 9 balls in the box.
