Addition and Subtraction
2026-02-28 12:53 Diff
https://brightchamps.com/en-us/math/numbers/addition-and-subtraction

Addition: If the sum of the column ≥ 10, carry 1 to next column.

Subtraction: If minuend digit < subtrahend digit, borrow 1 from the next left column.

Addition with Regrouping

First, we arrange the two digits in columns as ones and tens. Then start the addition with the ones column. If the result has two digits, write the last digit in the ones place and carry over the first digit to the tens column.

For example, if the sum is 15, write 5 in the ones place and carry over 1 to the tens column. Then, add the tens column along with the carried-over (1).

Let us take another example. Add numbers 366 + 455.

Step 1: Start with the digits in the ones column. 

6 + 5 = 11, carry over 1 to the tens place. 

Step 2: Now, we will add the tens place digits along with the carry-over 1. 

6 + 5 + 1 = 12. The sum’s tens place digit (1) will be carried over to the hundreds column. 

Step 3: Add the digits in the hundreds place along with the carry-over 1. 

3 + 4 + 1 = 8

Step 4: Thus, 366 + 455 = 821 

Subtraction with Regrouping

When a digit in the minuend is less than the matching digit in the subtrahend, we borrow 1 from the next preceding column and add it to the minuend to make it greater than the subtrahend. In this case, subtraction with regrouping occurs. For example, subtract the numbers 321 − 164.


Step 1: Start the subtraction with the ones place digits. Here, 1 is smaller than 4. So, we will borrow 1 from the tens column and make it 11. Now, 11 − 4 = 7. 

Step 2: Now, we can move to the tens place column. After giving 1 to the ones column, 2 becomes 1. Next, we can subtract 1 and 6. Here, 1 is smaller than 6, so again we borrow 1 from the hundreds column. After borrowing, the digit becomes 11 (i.e., 10 + 1) in that place-value column. So, 11 − 6 = 5. 

Step 3: We borrow 1 from the hundreds column, and 3 becomes 2. Now subtract the digits in the hundreds place. So, 2 − 1 = 1. 

Step 4: Thus, 321 − 164 = 157.