Let’s take an Example

283 is a 3 digit number.

 

Digits at hundreds place = 2

Digits at tens place = 8

Digit at units place of = 3

 

So, the number will be

Number = (Digits at hundreds place × 100)
  + (Digits at ten place × 10) + (Digit at units place × 1)

        = 2 × 100 + 8 × 10 + 3 × 1

        = 200 + 80 + 3

        = 283

 

To generalize

Number

Digits are interchanged

Let number be

    abc

 

So, Digit at hundreds place = a

      Digit at tens place = b

  & Digit at unit place = c

 

Number

  = (10 × Digit at hundreds place)  
     + (10 × Digit at tens place)  
      +  (1 × Digit at units place)

     = (10 × a) + (1 × b)

= 10a + b

Thus, number will be

    cba

 

So, Digit at hundreds place = c

      Digit at tens place = b

  & Digit at unit place = a

 

Number

  = (10 × Digit at tens place)  
      +  (1 × Digit at units place)

     = (10 × b) + (1 × a)

= 10b + a

  1. Chapter 2 Class 8 Linear Equations in One Variable
  2. Concept wise
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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.