Addition up to 9 Chapter Notes | Mathematics Class 1 ICSE PDF Download

What Is Addition?

• Putting two or more groups together to find out how many we have in all. 
• The symbol for addition is '+' read as 'plus'.
  

Some More Examples of Addition:
 

Addition can be done using fingers. Let's add 4 and 3 using fingers.

• Hold up 4 fingers.
• Then add 3 more fingers.
• Count all the raised fingers—there are 7.
• So, 4 + 3 = 7.

Addition on a Number Line

• Draw a line numbered 0 … 9.
• To add 2 + 3: start at 2, jump forward 3 hops, land on 5.
• The landing number (5) is the sum.

Here is another example: 

Adding Zero and One

+ 0: Adding zero means nothing is added, so the number stays the same.

• 4 + 0 = 4

+ 1: Adding one moves you to the very next number.

• 4 + 1 = 5

Why it works:

• Zero means “none,” so you don’t move.
• One means “one step forward” on the counting line.

Addition Fact:  When we add two numbers in any order, the answer does not change.

Number Fact: We can add different combinations of two numbers to get the same answer. 
For example, 1 + 7 = 8 and 2 + 6 = 8.

Addition of Three Numbers

1. Add the first two numbers.
2. Then add the third to that result.

Example: 2 + 3 + 2

• 2 + 3 = 5
• 5 + 2 = 7

Addition of Three Numbers on a Number Line

• Start at the first number on your line.
• Jump forward for the second number.
• From there, jump forward for the third number.

Example: 2 + 3 + 4

• Start at 2 → jump 3 → land on 5→ jump 4 → land on 9

Vertical Method of Addition

• Write numbers one under the other, lining up the ones place.
• Add down the column.

Word Problems

Question 2: Raju has 3 balls. His friend gives 2 more. How many balls now?
Answer: 3 + 2 = 5 → Raju has 5 balls.