Example of Addition
Adding Tens
How to add twodigit numbers (for example 30 + 40).
 First line up the numbers as per the place value (all the tens and the units lined up vertically). Put a line under the last number.
30
40
 Add the ones' place numbers. (0 + 0 = 0). Write the zero in the ones' place column.
30
40
0
 Add the tens' place digits (3 + 4 = 7) and write the answer below the line in the tens' place column.
30
40
70
Adding TwoDigit Numbers
How to add two twodigit numbers (for example 54 + 42).
 First line up the numbers as per the place value (all the tens and the units lined up vertically). Put a line under the last number.
54
42
 Add the numbers in the ones' place digits (4 + 2 = 6).
54
42
6
 Add the the tens' place digits(5 + 4 = 9) and write the answer below the line in tens' place column.
54
42
96
Adding Three OneDigit Numbers
Adding three numbers (for example 5 + 3 + 9) involves two steps.
 First line up the numbers as per the place value (all the tens and the units lined up vertically). Put a line under the last number.
 Add the first two digits. (5 + 3 = 8). Hold '8' in your mind.
 Add the other digit to this sum. (8 + 9 = 17).
Adding Hundreds
How to add threedigit numbers (for example 400 + 300).
 First line up the numbers as per the place value (all the hundreds,tens and the ones lined up vertically). Put a line under the last number.
400
300
 Add the numbers in the ones' place digits. (0 + 0 = 0) and write the answer below the line in the ones' place column.
400
300
0
 Add the tens' place numbers (0 + 0 = 0) and place the answer below the line and to the tens' place column
400
300
00
 Add the digits in the hundreds' place column (4+ 3 = 7) and write the answer below the line in the hundreds' place column.
400
300
700
Addition facts for 0, 1 and 2
The addition facts for 0, 1 and 2 are in the following table.
ZERO 
0+0=0 
0+1=1 
0+2=2 
0+3=3 
0+4=4 
ONE 
1+1=2 
1+2=3 
1+3=4 
1+4=5 
1+5=6 
TWO 
2+2=4 
2+3=5 
2+4=6 
2+5=7 
2+6=8 
When 0 is added to a second digit the answer is the second digit. (e.g. 0 + 6 = 6)
Adding 1 to any number is like counting up by 1.
Adding 2 to any number is like counting up by 2.
Mentally Adding TwoDigit Numbers
How to mentally add two twodigit numbers.
To add 73 and 34
 First add the digits in the ones' place(3 + 4)=7.
 Add digits in the tens' place(7 + 3) = 10.
 If the sum of ones's place numbers is single digit number then write the answer 107.
To add 65 and 87
 First add the digits in the ones' place(5 + 7)=12
 Add digits in the tens' place(6 + 8)=14
 If the sum of ones's place numbers is twodigit number then do the following
 Decrease the sum of ones's place by 10(1210= 2)
 Increase the sum of tens' place by 1(14 + 1=15)
 Write the sums of tens and ones' place together to get the answer of 152
Adding TwoDigit Numbers with Paper and Pencil
How to add two twodigit numbers (for example 35 + 78) with paper and pencil.
 First line up the numbers as per the place value (all the tens and the units lined up vertically). Put a line under the last number.
35
78
 Add the numbers in the ones' place. (5 + 8 = 13). This sum is a twodigit number so write 1 above the tens' place column and write the 3
below the line in the ones' place column.
1
35
78
3
 Add the digits in the tens' place column (1 + 3 + 7 = 11) and write the answer below the line in the tens' place column.
1
35
78
113
Addition with calculator
Here are the steps to add twodigit numbers (for example 67 + 89) using calculator
 Type the first number 67 by presing the 6 button and the 7 button
 Press + button
 Type the second number 89 by pressing the 8 button and the 9 button
 Press the = button to get the answer.
Estimating a sum by rounding
How to Estimate a sum by rounding.
 Round each twodigit number
 Add the rounded numbers to get the best estimate.
For example, estimate the following sums:
46 + 31, 64 + 25, and 45 + 34
46 + 31 = 50 + 30 = 80
64 + 25 = 60 + 30 = 90
45 + 34 = 50 + 30 = 80
