Math Help: Partial Sum Addition

Help with Partial Sum Addition

How to Do Partial Sum Addition

Partial sum addition means adding 2 numbers using columns based on place values. You add together the 2 numbers in the ones place, and that tells you what the ones place of your answer will be. If that number is 10 or greater, you only use the ones part of the answer, and you add a 1 to the tens column.

Next, you add up all of the numbers from the tens column (plus any 1 carried over from the previous column). The answer tells you the value of the tens digit in your answer. Repeat the process until you've added up every column. Below is a step-by-step example of how to add together 2 multi-digit numbers, like 746 + 92.

1. Write the larger number on top and the smaller number directly below it. Be sure the place values are aligned. For 746 + 92, the 2 will be directly below the 6 in 746 and the 9 will be below the 4.

2. Draw a horizontal line underneath the smaller number. You'll write your answer underneath this line.

3. Add together the numbers in the ones place and write the answer below the line, directly below the ones place of the smaller number. For this problem, you'd add 6 + 2 to get 8, and then write the 8 under the 2.

4. Move on to the tens place. Here, you'll add 4 + 9 to get 13. If the answer had been a single-digit number, you would just write the answer underneath the line, directly under the tens place. However, since the answer has 2 digits, you'll write the number in the answer's ones place (3) and then add the 1 to the next column.

5. Add together the numbers in the hundreds place. Since 92 has no hundreds place, you'll just add the 7 from 746 to the 1 that you brought over from the tens column. You'll add 7 + 1 to get 8, so your final answer is 838.

6. You can always check your answer by subtracting one of the two addends (numbers being added) from your answer. If you added correctly, then the result should be the other addend. If you haven't learned to subtract multi-digit numbers yet, keep this advice in mind, because you'll most likely be learning it soon.

Practice Problems

1. 23 + 81 = ?

2. 175 + 25 = ?

3. 569 + 90 = ?

4. 143 + 973 = ?

5. 1,482 + 82 = ?

Answers

1. 23 + 81 = 104

2. 175 + 25 = 200

3. 569 + 90 = 659

4. 143 + 973 = 1,116

5. 1,482 + 82 = 1,564