How to add three-digit numbers (for example 600 + 500).

• Place one number above the other so the hundreds' place digits, the tens' place digits and ones' place digits are lined up. Draw a line under the bottom number.

600
500

• Add the two ones' place digits. (0 + 0 = 0).

600
500
  0

• Add the numbers in the tens' place column (0 + 0 = 0) and place the answer below the line and to the left of the ones' place sum.

 600
 500
  00

• Add the numbers in the hundreds' place column (6 + 5 = 11) and place the answer below the line and to the left of the tens' place sum.

  600
  500
 1100