Lesson: Adding Within 1,000

Objective

In this lesson, we will learn how to add numbers within 1,000 using various strategies.

Steps for Adding Numbers

1. Align the Numbers: Write the numbers one on top of the other, aligning them by their place values (units, tens, hundreds).
2. Start from the Right: Begin adding from the rightmost column (units) and move to the left.
3. Carry Over if Necessary: If the sum of the digits in a column is 10 or greater, write down the last digit and carry over the 1 to the next column to the left.

Example

Let's add 478 and 256:

1. Align the numbers:

     478
   + 256
   

2. Add the units column (8 + 6):

   • $8 + 6 = 14$. Write down 4 and carry over 1.

     478
   + 256
   ----
       4 (write down 4)
   

3. Add the tens column (7 + 5 + 1):

   • $7 + 5 + 1 = 13$. Write down 3 and carry over 1.

     478
   + 256
   ----
      34 (write down 3)
   

4. Add the hundreds column (4 + 2 + 1):

Thus, $478 + 256 = 734$.

Key Questions

• What is the first step in adding two numbers?
• Why do we carry over a number?
• How do you know when to write down a digit and when to carry over?

Keywords

• Addition
• Carry Over
• Place Value
• Sum