Adding 2-Digit Numbers with Regrouping

Here we will learn adding 2-digit numbers with regrouping and start working with easy numbers to get acquainted with the addition of two numbers.

Regrouping Tens and Ones:

In the addition of numbers, if the sum of digits in the ones column is more than 9, then we regroup the sum.

Look at the example:

This is called regrouping of ones to tens and ones. Regrouping makes the addition easier.

1. Let us add 35 and 27.

5 tens 12 ones can be regrouped as

So, 35 + 27 = 6 tens 2 ones = 62

Note:

We never write two digits together under any place. Left digit always belongs to the next place.

Let us take the following example:

2. Sam has collected 24 leaves and Jane has 7 leaves. How many leaves they have in all?

3. Let us add 17 and 26.

Start by adding the ones. 7 ones and 6 ones are 13 ones.

But 13 ones = 1 ten and 3 ones.

So, regroup the ones by making another bundle of 10 matchsticks.

3 loose matchsticks are left.

Add the tens. 1 ten, 1 ten (regrouped) and 2 tens make 4 tens.

So, the sum of 17 and 26 is 43.

Let us take another example.

4. 38 + 14 = ?

38 + 14 = 52

Note:

In addition 'regrouping' is also known as 'carry over'.

How to add two two-digit numbers with carrying?

Let us follow the steps and start learning adding 2-digit numbers with regrouping with the help of these examples.

1. Now, let us add 17 and 26 the short way.

Write the numbers one below the other as shown.

The sum is 43.

2. 45 + 37

(i) First arrange the numbers vertically so that the tens' place digits and ones' place digits are lined up which means in simple one number should be written above the other number. Draw a line under the bottom number.

(ii) Add the ones place digits. Add (5 + 7 = 12). Place 2 in the ones column and place 1 above the tens column as shown.

(iii) Then add the tens' place digits. Add (4 + 3 + 1 = 8) and place 8 in the tens column as shown.

(iv) The answer of the sum 45 + 37 is 82.

Method II: 45 + 37

Add the ones place:

5 ones + 7 ones = 12 ones

Regroup 12 ones

12 ones = 10 ones + 2 ones

= 1 ten + 2 ones

Place 2 in the ones answer column and place 1 in the tens carry-up column.

Add the tens place:

4 tens +3 tens + 1 tens = 8 tens

Place 8 in the tens answer column.

So, adding 45 + 37 = 82.

3. 58 + 39

(i) First arrange the numbers vertically so that the tens' place digits and ones' place digits are lined up which means in simple one number should be written above the other number. Draw a line under the bottom number.

(ii) Add the ones place digits. Add (8 + 7 = 17). Place 7 in the ones column and place 1 above the tens column as shown.

(iii) Then add the tens' place digits. Add (5 + 3 + 1 = 9) and place 9 in the tens column as shown.

(iv) The answer of the sum 58 + 39 is 97.

Method II: 58 + 39

Add the ones place:

8 ones + 9 ones = 17 ones

Regroup 17 ones

17 ones = 10 ones + 7 ones

= 1 ten + 7 ones

Place 7 in the ones answer column and place 1 in the tens carry-up column.

Add the tens place:

5 tens +3 tens + 1 tens = 9 tens

Place 9 in the tens answer column.

So, adding 58 + 39 = 97.

Regrouping Tens to Hundreds:

When the sum of digits in the tens place is more than 9, then we regroup the number in tens and hundreds.

4. Let us add 93 and 21

10 tens is one hundred

5. Let us add 49 and 64. Add the ones and regroup 9 ones + 4 ones = 13 ones. 13 ones = 1 ten and 3 ones Write 3 in ones place and carry over 1 ten to the tens column. Add the tens 1 + 4 + 6 = 11 tens 11 tens = 1 hundred and 1 ten Write 1 ten at tens place and carry over 1 hundred to hundreds column.

6. Let us add 28, 34 and 50. Add the ones and regroup 8 ones + 4 ones + 0 ones = 12 ones. 12 ones = 1 ten and 2 ones Write 2 in ones place and carry over 1 ten to the tens column. Add the tens 1 + 2 + 3 + 5 = 11 tens 11 tens = 1 hundred and 1 ten Write 1 ten at tens place and carry over 1 hundred to hundreds column.

7. A shopkeeper had 54 toy cars and 28 planes. How many toy cars and planes did the shopkeeper have in all?

54 + 28 = ?

Step I: First add the ones. 4 + 8 = 12 ones. Write 2 under ones column and carry 1 tens to the tens column.

Step II: Next add the tens. 5 + 2 + 1 = 8 tens. Write 8 under tens column.

So, there are 82 toy cars and plane in all.

Worksheet on Adding 2-Digit Numbers with Regrouping:

1. Add the following Regrouping Tens and Ones:

(i) 34 + 8

(ii) 16 + 9

(iii) 38 + 5

(iv) 88 + 3

(v) 73 + 8

(vi) 49 + 3

Answer:

1. (i) 42

(ii) 25

(iii) 43

(iv) 91

(v) 81

(vi) 52

2. Add the following Regrouping Tens and Ones:

(i) 37 + 55

(ii) 37 + 26

(iii) 29 + 66

(iv) 56 + 27

(v) 19 + 73

(vi) 13 + 77

(vii) 62 + 29

(viii) 36 + 46

(ix) 28 + 17

(x) 25 + 47

(xi) 13 + 39

(xii) 54 + 17

Answer:

2. (i) 92

(ii) 63

(iii) 95

(iv) 83

(v) 92

(vi) 90

(vii) 91

(viii) 82

(ix) 45

(x) 72

(xi) 52

(xii) 71

3. Add the following Regrouping Tens to Hundreds:

(i) 76 + 92

(ii) 21 + 84

(iii) 99 + 86

(iv) 87 + 55

(v) 44 + 96

(vi) 59 + 66

(vii) 32 + 91

(viii) 41 + 77

(ix) 82 + 38

(x) 24 + 95

(xi) 90 + 60

(xii) 51 + 82

Answer:

3. (i) 168

(ii) 105

(iii) 185

(iv) 142

(v) 140

(vi) 125

(vii) 123

(viii) 118

(ix) 120

(x) 119

(xi) 150

(xii) 133

2nd Grade Math Practice

From Adding 2-Digit Numbers with Regrouping to HOME PAGE