2 digit by 1 digit multiplication with regrouping

Here we will learn multiplying 2-digit number by 1-digit number. In two different ways we will learn to multiply a two-digit number by a one-digit number.

Examples of multiplying 2-digit number by 1-digit number without Regrouping:

We will have a quick review of multiplication of 2-digit number by 1-digit number without regrouping:

1. Multiply 34 and 2

Solution:

Step I: Arrange the numbers vertically.

Step II: First multiply the digit at the ones place by 2.

2 × 4 = 8 ones

Step III: Now multiply the digit at the tens place by 2.

2 × 3 = 6 tens

Thus, 34 × 2 = 68

2. Multiply 20 by 3 by using expanded form

Solution:

                   20         →                           2 tens + 0 ones

              ×    3         →                                       ×      3

                                                            6 tens + 0 ones

                                                          = 60 + 0

                                                          = 60

Therefore, 20 × 3 = 60

3. Multiply 50 by 1 by using short form

Solution:

         50                      →                50                     

    ×    1                      →             ×   1

          0                                           50

(i) First digit of one’s place is multiplied by 1, i.e., 0 × 1 = 0

(ii) Then digit at ten’s place is multiplied by 1, i.e., 5 tens × 1 = 5 tens

Hence, 50 × 1 = 50

4. Multiply 25 by 3

Step I: Arrange the numbers vertically.

Step II: First multiply the digit at the ones place by 3.

3 × 5 = 15 = 1 ten + 5 ones

Write 5 in the ones column and carry over 1 to the tens column

Step III: Now multiply the digit at the tens place by 3.

3 × 2 = 6 tens

Now, 6 + 1 (carry over) = 7 tens

Thus, 25 × 3 = 75

5. Multiply 46 by 4

Step I: Arrange the numbers vertically.

Step II: Multiply the digit at the ones place by 4.

6 × 4 = 24 = 2 tens + 4 ones

Write 4 in the ones column and carry over 2 to the tens column

Step III: Now multiply the digit at the tens place by 4.

4 × 4 = 16 tens

Now, 16 + 2 (carry over) = 18 tens = 1 hundred + 8 tens

Write 8 at the tens place and 1 at the hundred place.

Thus, 46 × 4 = 184

6. Multiply 20 by 3 by using expanded form

Solution:

                   20         →                           2 tens + 0 ones

              ×    3         →                                       ×      3

                                                            6 tens + 0 ones

                                                          = 60 + 0

                                                          = 60

Therefore, 20 × 3 = 60

7. Multiply 26 by 7 by using expanded form 

Solution:

              26          →       20 + 6          →                      2 tens + 6 ones

       ×      7          →         ×   7           →                          ×     7

                                                                  (2 × 7) tens + (6 × 7) ones

        2 tens + 6 ones

×                  7 ones

   14 tens + 42 ones

= 14 tens + (40 + 2) ones

= 14 tens + 4 tens + 2 ones

= 18 tens + 2 ones

= 180 + 2

= 182

Therefore, 26 × 7 = 182

8. Multiply 48 by 6 by using short form

Solution:

                 48

        ×         6

         24 ← 48

= 28 tens 8 ones

= 288

Hence, 48 × 6 = 288

(i) 48 × 6 is written in column from.

(ii) 8 ones are multiplied by 6, i.e., 6 × 8 = 48 ones = 4 tens + 8 ones

8 is written is one’s column and 4 tens is gained.

(iii) Gained 4 is carried to the ten’s column.

(iv) Now 4 tens is multiplied by 6, i.e., 4 tens × 6 = 24 tens

(v) Carried 4 tens is added to 24 tens, i.e., 4 tens + 24 tens = 28 tens

9. Find the product of 58 × 5.

Solution:

                 58

              ×   5

          25 ← 40 

 = 25 + 4 ← 0

 = 29          0

 = 290

(i) 8 ones × 5 = 40 = 4 tens + 0 one

(ii) 5 tens × 5 = 25 tens

(iii) 25 tens + 4 tens = 29 tens

Hence, 58 × 5 = 290

10. Multiply 37 by 8

Solution:

                3  7

        ×          8

               5   6

     +   2   4   0

          2   9    6

(i) 7 ones × 8 = 56 ones = 5 tens 6 ones

56 is placed in such way that 5 comes under tens and 6 under ones

(ii) 3 tens × 8 = 24 tens = 240 ones

= 2 hundreds, 4 tens and 0 ones

240 is placed below 56 in such way that 2 comes under hundreds, 4 under tens and 0 under ones.

Hence, 37 × 8 = 296

Questions and Answers on Multiplying 2-Digit Number by 1-Digit Number:

Multiplication of 2-Digit Number by 1-Digit Number Without Regrouping:

I. Find the product:

(i) 23 × 3 =

(ii) 44 × 2 =

(iii) 33 × 2 =

(iv) 22 × 4 =

(v) 32 × 3 =

(vi) 40 × 2 =

(vii) 43 × 2 =

(viii)  12 × 3 =

(ix) 23 × 2 =

(x) 11 × 9 =

(xi) 21 × 4 =

(xii) 13 × 3 =

Answer:

I. (i) 69

(ii) 88

(iii) 66

(iv) 44

(v) 96

(vi) 80

(vii) 86

(viii) 36

(ix) 46

(x) 99

(xi) 84

(xii) 39

Multiplication of 2-Digit Number by 1-Digit Number With Regrouping:

II. Find the product:

(i) 46 × 2

(ii) 19 × 4

(iii) 27 × 3

(iv) 18 × 5

Answer:

II. (i) 92

(ii) 76

(iii) 81

(iv) 90

III. Multiply the following:

(i) 78 × 4

(ii)  63 × 6

(iii) 51 × 6

(iv) 39 × 8

(v) 72 × 9

(vi) 45 × 7

(vii) 17 × 4

(viii) 88 × 8

Answer:

III. (i) 312

(ii)  398

(iii) 306

(iv) 312

(v) 648

(vi) 315

(vii) 68

(viii) 704

IV. Solve the following:

(i) 37 × 6

(ii) 72 × 4

(iii) 56 × 7

(iv) 84 × 2

(v) 45 × 9

Answer:

IV. (i) 37 × 6

(ii) 72 × 4

(iii) 56 × 7

(iv) 84 × 2

(v) 45 × 9

2nd Grade Math Practice

From Multiplying 2-Digit Number by 1-Digit Number to HOME PAGE

Didn't find what you were looking for? Or want to know more information about Math Only Math. Use this Google Search to find what you need.

How does regrouping work in multiplication?