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.

Examples of multiplying 2-digit number by 1-digit number:

1. 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


2. 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


3. 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


4. 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


5. 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


6. 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


2nd Grade Math Practice

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