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Adding Two Digit Numbers with Regrouping
Step 1: Column up the Addition.
What is Adding Two-Digit numbers?
Adding Two-Digit numbers is simple and type of fun math and easy math too. This lesson shows you how to teach your child the “carrying method in addition” which is also known as “regrouping in addition”. Guide your child who is at this stage of addition to work out sums using his mental math knowledge so as to speed up his homework or school worksheets. Let’s start with Adding Two-Digit numbers as follows;
The sum above is a column addition. Here, to begin with adding two-digit numbers, I have taken the two numbers 27 and 35. Both numbers have two place values. They are Tens and Units. The Tens column is named as “T” and the Units column is named as “U”.
Step 2: Add the Units (Ones) first.
Now you must teach the child the importance of adding the Units column first in adding two-digit numbers. Otherwise, in most cases children directly attempt to add the Tens column because it is the first column. Teach the child that in adding two-digit numbers we must first add the smaller values and then the bigger values. Units are the smallest in value so; we must first add the Units column. At this point try to make them understand that this is the rule in adding two-digit numbers and we must follow this otherwise the final answer will be completely different and wrong.
Now let’s add the Units column. If possible cover the Tens column (do not erase) so that the child can clearly see what is there to add in the Units column. The two numbers which we have to add in the Units column are 7 and 5. This is easy math for a child who starts learning to add two-digit numbers. Let the child come up with the answer with his mental math knowledge. It’s 12.
Total of the Units Column
Step 3: How to place numbers bigger than 9 in a column?
Now it’s your time to write the answer under the Units column. But, can we write a two-digit number in the Units column as shown below? Tell the child that if he does so, it’s completely wrong.
Incorrect way of placing a Two-Digit number in the Units Column
How to place a Two-Digit number in the Units Column?
Now explain the concept to the child. This is because the largest digit that can be in any place value is 9. Therefore, the largest number that the Units column can keep with it is 9. But the answer we got is 12. It is greater than 9. So, what should we do with the value 12.
Comparison of the total of the Units Column with 9
Placing the two digits of number 12 under the correct columns
Now show the child that number 12 has 2 Units and 1 Ten in it. So, in number 12, 2 belongs to the Units column and 1 belongs to the Tens column. Therefore, write only 2 under the Units column and carry the 1 Ten to the Tens column.
Applying the carrying method in Adding Two-Digit numbers
Step 4: Adding up the Tens Column
Now, we've got three digits to add in the Tens column. They are 1, 2 and 3. This is also an easy task for your child. Let’s add them and the answer is 6.
Total of the Tens Column
Comparison of the total of the Tens Column with 9
So, now we can write number 6 under the Tens column. Then the final answer is 62.
Adding Two-Digit numbers total
Try another few more sums as above with your child. I’m sure he will find how easy Two-Digit Number Addition is within no time. It is hard to find websites that have online activities for carrying method in addition. But I found this website, www.k8schoollessons.com which consists of attractive online fun math activities of carrying method in Addition which your child can do easy math with workings too.