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 numbers are not divisible by 3?

556500 , 425421 , 910665, 514518, 432771, 648720,976430

Right Option : D
View Explanation
Explanation
Question : 2

If 5476a is divisible by 3, then what can be the value of a?

Right Option : B
View Explanation
Explanation
Question : 3

Which of the following number is divisible by 3?

121 , 543 , 665 , 875

Right Option : B
View Explanation
Explanation
 
 


Students / Parents Reviews [20]