Divisibility Rule of 3


 
 
Concept Explanation
 

Divisibility Rule of 3:

Any natural number is divisible by 3 if the sum of its digits is also divisible by 3.

Justification:

Let us first consider case of a two digit number:

 n=overline{ab} be a two digit number. Then, n can be written as

         n = 10a + b, where b is units digit of n.

Rightarrow    n = 9a + a + b

Rightarrow    n = a multiple of 9 + ( a + b )

Since a multiple of 9 is also a multiple of 3, so

Rightarrow    n is a multiple of 9, if ( a + b ) is a multiple of 3

Thus, a two digit number is divisible by 3, if the sum of its digits is divisible by 3.

.... (More Text Available, Login?)
Sample Questions
(More Questions for each concept available in Login)
Question : 1

Which of the following number is divisible by 3?

561 , 322 , 905, 617

Right Option : A
View Explanation
Explanation
Question : 2

Which of the following number is not divisible by 3?

783 , 431 , 825, 678

Right Option : B
View Explanation
Explanation
Question : 3

If a 4 digit number A is divisible by 3, then which of the following is correct?

Right Option : A
View Explanation
Explanation
Chapters
Content / Category
Class / Course
 
 


Students / Parents Reviews [10]