# IMO Class 1 Chapter 2: Addition – (Two Digits)

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### IMO Class 1 Chapter 2: Addition – (Two Digits) Detailed Notes

2 digit addition is a type of addition in which only two digits are arranged in their respective place values. 2 digit addition can also be done mentally by following a few simple steps. Two-digit addition is one of the simplest types of addition. Let’s go over the fundamentals of adding two-digit numbers together.

2 digit addition is performed by remembering the place value of numbers. Two-digit numbers have the same place value as ones and tens. When adding two digits, we arrange the numbers in a column under the appropriate place value. This method aids in the addition of digits one by one. There are two methods for doing 2-digit addition: addition with regrouping (carrying forward) and addition without regrouping (no carrying forward). The numbers being added are known as addends, and the result of adding these numbers is known as their sum. Examine the graph below, which shows that the addends are 70 and 15, and the sum is 85.

### 2 Digit Addition With Regrouping

The addition of two digits and 2 digit addition with regrouping is a method in which if the sum of the numbers in one column is greater than 9, the number is carried forward to the next column. In the case of two-digit numbers, regrouping or carrying forward begins in the one’s column and progresses to the tens column. The steps below demonstrate two-digit addition with regrouping:

Step 1: Arrange the numbers or addends in columns based on their place value, i.e., ones and tens.

Step 2: Begin adding numbers from the right, i.e., the one’s column, and work your way to the left, i.e., the tens column.

Step 3: If the sum of the one’s column is greater than 9, we get another double-digit number. The number from the one’s column is placed under the one’s column, and the tens number is carried forward or regrouped to the tens column of the original numbers.

Step 4: When adding the tens column, we include the tens number carried over from the one’s column.

Step 5: After adding both columns, we get the final total.

Let’s look at an example to better understand the steps. Add 59 to 23.

As shown in the above image, we obtained the sum by adding 59 and 23 using the regrouping method. Here’s a step-by-step breakdown:

Step 1: Sort the numbers 59 and 23 by place value. In the one’s column, there are 9 and 3, and in the tens column, there are 5 and 2.

Step 2 + 3: Add 9 + 3 to get 12 We carry forward 1 to the tens column and write 2 as the sum in the one’s column because 12 is greater than 9.

Step 4: Include the one from the column that was carried forward. As a result, we add 5 + 2 + 1 = 8.

Step 5: Both columns are now added. As a result, 59 + 23 = 82.

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