Multiplying 2-Digit Number by 1-Digit Number

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.


I: 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 24 by 2.

               T     O

               2     4

            ×        2

               4     8

First multiply the ones by 2.

× 2 = 8.

Write 8 under O.

Now multiply the tens by 2.

2 × 2 = 4.

Write 4 under T.

Thus, 24 × 2 = 48


2. 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

Multiplying 2-Digit Number by 1-Digit Number

Thus, 34 × 2 = 68


3. 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


4. 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


5. Multiply 34 by 2.

We can multiply a given 2-digit number by a 1-digit number by vertical method.

Multiply the Digit in the Ones Place

Step I: Arrange the numbers in correct place.

Multiply the digit in the ones place by 2.

4 × 2 = 4 × 2 = 8 or 8 ones

Write 8 in the ones column.


Multiply the Digit in the Tens Place

Step II: Multiply the digit in the tens place by 2.

3 tens × 2 = 30 × 2 = 60 or 6 tens.

Write 6 in tens column.


So, 34 × 2 = 68


MULTIPLICATION OF A 2-DIGIT NUMBER BY A 1-DIGIT NUMBER WITHOUT REGROUPING:

6. Let us multiply 24 by 2.

Write the numbers one below the other as shown.

Multiply 2-Digit by 1-Digit

Step I: Multiply the ones digit by 2.

4 ones × 2 = 8 ones

Write 8 in the ones place.


Step II: Multiply the tens digit by 2. 

2 tens × 2 = 4 tens

Write 4 in the tens place.


The product is 48.


Observe the following Example using Three Different Methods:

7. Multiply 13 by 2.

Solution:

First Method: Using Repeated Addition.

13 x 2 = 13 + 13 = 26

Therefore, 13 x 2 = 26.


Second Method: Using Expanded Form

Consider 13 as 10 + 3.

13 × 2 = (10 + 3) × 2

           = 10 × 2 + 3 × 2

           = 20 + 6

           = 26.


Third Method: Short Form

Write the numbers according to place value shown on the right.

Step I:

Multiply the ones:

3 ones × 2 = 6 ones

Write 6 under ones column.


Step II:

Multiply the tens:

1 ten × 2 = 2 tens

Write 2 under tens column.

Thus, the product of 13 and 2 is 26.


II: Examples of multiplying 2-digit number by 1-digit number with Regrouping:

1. Multiply 66 by 3

               T     O

               1

               6     6

            ×        3

         1     4     8

First multiply the ones by 3.

× 3 = 18 = one ten + 8 ones

Write 8 under O. carry 1 ten

Now multiply the tens by 3.

6 × 3 = 18

Add 1 to the product.

18 + 1 = 19


2. 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

Multiplying 2-Digit Number by 1-Digit Number with Regrouping

Thus, 25 × 3 = 75


3. 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.

Multiply 2-Digit Number by 1-Digit Number with Regrouping

Thus, 46 × 4 = 184


4. 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


5. 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


6. 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


7. 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


8. 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


Multiplication with Regrouping Once:

9. Let us multiply 27 by 3.

Write the numbers one below the other as shown.

Multiplication 2-Digit by 1-Digit Number with Regrouping Once

Step I: Multiply the ones digit by 3.

7 ones × 3 = 21 ones

Regroup: 21 ones = 2 tens and 1 one

Write 1 in the ones place.

Carry over 2 tens and write it under T.


Step II: Multiply the tens digit by 3.

2 tens × 3 = 6 tens

Add 6 tens and tens (carried over)

= 6 tens + 2 tens (carried over)

= 8 tens

Write 8 in the tens place.

The product is 81.


Multiplication with Regrouping Twice:

10. Let us multiply 53 by 4.

Write the numbers one below the other as shown.

Multiplication 2-Digit by 1-Digit with Regrouping Twice

Step I: Multiply the ones digit by 4.

3 ones × 4 = 12 ones

Regroup: 12 ones = 1 tens and 2 ones

Write 2 in the ones place.

Carry over 1 ten and write it under T.


Step II: Multiply the tens digit by 4.

5 tens × 4 = 20 tens

Add 20 tens and ten (carried over)

= 20 tens + 1 ten = 21 tens

Regroup: 21 tens = 2 hundreds and 1 ten

Write 1 in the tens place.

Carry over 2 hundreds and write it under H.


Step III: Write 2 in the hundreds place.


The product is 212.


Word Problems on Multiplying a 2-digit Number by a 1-digit Number:

11. Robert can paint 45 pictures in a month. How many pictures can he paint in 3 months?

Multiply the digit in the ones place by 3

Step I: Multiply the digit in the ones place by 3. If the result is a 2-digit number, keep the ones and carry over the tens.

5 × 3 = 15

Keep 5 in the ones column and carry over 1 to the tens column.

Multiply the digit in the tens place by 3

Step II: Multiply the digit in the tens place by 3. Add the carried over number to the result. If it is a 2-digit number, keep the ones and carry over the tens to the hundreds column.

4 × 3 = 12

12 + 1 = 13

Keep 3 at the tens place and carry over 1 to the hundreds column.

Write the carried over digit


Step III: Write the carried over digit in the hundreds column.



Thus, Robert can paint 135 pictures in 3 months.


Worksheet 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


V. Multiply the following :

(i)

                    T     O

                    3     1

                    ×    2 

                 _______

(ii)

                    T     O

                    4     7

                    ×    1 

                 _______

(iii)

                    T     O

                    1     1

                    ×    3 

                 _______

(iv)

                    T     O

                    2     2

                    ×    2 

                 _______

(v)

                    T     O

                    2     3

                    ×    2 

                 _______

(vi)

                    T     O

                    2     6

                    ×    3 

                 _______

(vii)

                    T     O

                    4     9

                    ×    2 

                 _______

(viii)

                    T     O

                    2     3

                    ×    4 

                 _______

(ix)

                    T     O

                    1     6

                    ×    6 

                 _______

(x)

                    T     O

                    1     9

                    ×    5 

                 _______

(xi)

                    T     O

                    5     2

                    ×    5 

                 _______

(xii)

                    T     O

                    2     3

                    ×    6 

                 _______

(xiii)

                    T     O

                    6     4

                    ×    9 

                 _______

(xiv)

                    T     O

                    3     2

                    ×    7 

                 _______

(xv)

                    T     O

                    7     5

                    ×    8 

                 _______

Answer:

III. (i) 62

(ii) 47

(iii) 33

(iv) 44

(v) 46

(vi) 78

(vii) 98

(viii) 92

(ix) 96

(x) 95

(xi) 260

(xii) 138

(xiii) 576

(xiv) 224

(xv) 600


VI. Multiply the following:

(i) 21 × 5 = _____

(ii) 34 × 2 = _____

(iii) 23 × 3 = _____

(iv) 27 × 3 = _____

(v) 38 × 2 = _____

(vi) 18 × 4 = _____

(vii) 25 × 8 = _____

(viii) 32 × 6 = _____

(ix) 29 × 4 = _____

(x) 45 × 5 = _____


Answer:

VI. (i) 105

(ii) 68

(iii) 69

(iv) 81

(v) 76

(vi) 72

(vii) 200

(viii) 192

(ix) 116

(x) 225


VII. Find the following products in your notebook.

(i)

                    T     O

                    2     9

                    ×    7 

                 _______

(ii)

                    T     O

                    6     3

                    ×    4 

                 _______

(iii)

                    T     O

                    3     8

                    ×    7 

                 _______

(iv)

                    T     O

                    6     6

                    ×    4 

                 _______

(v)

                    T     O

                    5     4

                    ×    7 

                 _______

(vi)

                    T     O

                    3     5

                    ×    4 

                 _______

(vii)

                    T     O

                    6     9

                    ×    8 

                 _______

(viii)

                    T     O

                    8     5

                    ×    4 

                 _______

(ix)

                    T     O

                    8     0

                    ×    4 

                 _______

(x)

                    T     O

                    5     8

                    ×    8 

                 _______

(xi)

                    T     O

                    5     1

                    ×    7 

                 _______

(xii)

                    T     O

                    6     3

                    ×    8 

                 _______


Answer:

VIII. (i) 203

(ii) 252

(iii) 266

(iv) 264

(v) 378

(vi) 140

(vii) 552

(viii) 340

(ix) 320

(x) 464

(xi) 357

(xii) 504



VIII. Find the products:

(i) 27 × 4 = __________

(ii) 5 × 10 = __________

(iii) 25 × 9 = __________

(iv) 16 × 4 = __________

(v) 14 × 8 = __________ 

(vi) 37 × 7 = __________

(vii) 63 × 4 = __________

(viii) 2 × 70 = __________

(ix) 53 × 5 = __________


Answer:

VIII. (i) 108

(ii) 50

(iii) 225

(iv) 64

(v) 112

(vi) 259

(vii) 252

(viii) 140

(ix) 265


IX. Word Problem on Multiplying 2-Digit Number by 1-Digit Number:

(i) A month has 30 days. How many days be there in 3 such months?

Answer:

IX. (i) 90 days

You might like these






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.



New! Comments

Have your say about what you just read! Leave me a comment in the box below. Ask a Question or Answer a Question.




Share this page: What’s this?

Recent Articles

  1. Patterns in Numbers | Patterns in Maths |Math Patterns|Series Patterns

    Dec 13, 24 08:43 AM

    Complete the Series Patterns
    We see so many patterns around us in our daily life. We know that a pattern is an arrangement of objects, colors, or numbers placed in a certain order. Some patterns neither grow nor reduce but only r…

    Read More

  2. Patterns in Math | Missing Number | Counting Numbers | Worksheets

    Dec 13, 24 12:31 AM

    Finding patterns in math is very important to understand the sequence in the series. We need to find the exact missing number that from the group of numbers. The counting numbers may be counting

    Read More

  3. Concept of Pattern | Similar Patterns in Mathematics | Similar Pattern

    Dec 12, 24 11:22 PM

    Patterns in Necklace
    Concept of pattern will help us to learn the basic number patterns and table patterns. Animals such as all cows, all lions, all dogs and all other animals have dissimilar features. All mangoes have si…

    Read More

  4. 2nd Grade Geometry Worksheet | Plane and Solid Shapes | Point | Line

    Dec 12, 24 10:31 PM

    Curved Line and Straight Line
    2nd grade geometry worksheet

    Read More

  5. Types of Lines |Straight Lines|Curved Lines|Horizontal Lines| Vertical

    Dec 09, 24 10:39 PM

    Types of Lines
    What are the different types of lines? There are two different kinds of lines. (i) Straight line and (ii) Curved line. There are three different types of straight lines. (i) Horizontal lines, (ii) Ver…

    Read More