2. Everyday Mathematics Partial-Sums Addition

3. Partial-Sums Addition Partial-sums addition involves: Understanding place value; Finding partial sums; and Adding partial sums to get the final answer. Everyday Mathematics

4. Partial-Sums Addition Solve: 634 + 918 We begin by thinking of the expanded notation for the numbers being added. 634 = 600 + 30 + 4 918 = 900 + 10 + 8 With partial-sums addition, we can start from the right or the left. Children often prefer to start from the greatest place-value position. Everyday Mathematics

5. Partial-Sums Addition First we add the hundreds. 634 + 918 600 + 900 =1,500 The numbers written in blue show our thinking and the numbers written in black show what we write to solve the problem. Everyday Mathematics

6. Partial-Sums Addition Next we add the tens. 634 + 918 600 + 900 =1,500 30 + 10 =40 Everyday Mathematics

7. Partial-Sums Addition Then we add the ones. 634 + 918 600 + 900 =1,500 30 + 10 =40 4 + 8 =12 Everyday Mathematics

8. Partial-Sums Addition Finally, we add the partial sums to find the answer. 634 + 918 1,500 634 + 918 = 1,552 40 + 12 1,552 Everyday Mathematics

9. Partial-Sums Addition Everyday Mathematics When children use partial-sums addition, they practice skills related to number sense and algebraic reasoning. For example: Understanding and using place value; Thinking about numbers in expanded notation; and Using addition fact extensions such as 600 + 900 = 1,500. If children work from left to right, which is generally their inclination, they begin the problem-solving process with a reasonable estimate of what the final answer should be.