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Examples :: Math :: Example of Easy Addition

Example of Addition

Adding Tens

How to add two-digit 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 Two-Digit Numbers

How to add two two-digit 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 One-Digit 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 three-digit 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 Two-Digit Numbers

How to mentally add two two-digit 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 two-digit number then do the following
    • Decrease the sum of ones's place by 10(12-10= 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 Two-Digit Numbers with Paper and Pencil

How to add two two-digit 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 two-digit 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 two-digit 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 two-digit 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