Divisibility Rule of 7


 
 
Concept Explanation
 

Divisibility Rule of 7

Divisibility Rule of 7:

To check for the divisibility of 7, take the last digit of the number, double it and subtract the doubled number from the remaining number. If the result is divisible by 7 (e.g. 14, 7, 0, -7, etc.), then the number is divisible by 7.

Illustration: Check whether 3101 is divisible by 7?

Solution:  Step 1: take off the last digit of the number which is 1  

 Step 2: Double the last digit. So, it becomes 2.

Step 3: Subtract 2 from the remaining number i.e. 310. So, we obtain 310 - 2 = 308.

Step 4: Repeat the process by taking off the 8 from 308.

Step 5: Double it and subtract from the remaining number. So, 30 - 16 = 14

Step 6:  The result is 14 which is a multiple of 7.

Hence, 3101 is divisible by 7.

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Sample Questions
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Question : 1

Which of the following number is not divisible by 7 ?

843, 642

Right Option : C
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Explanation
Question : 2

Which of the following number is divisible by 7 ?

868, 539

Right Option : C
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Explanation
Question : 3

Which of the following numbers are divisible by 7 :

343, 133, 329, 278

Right Option : D
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Explanation
 
 


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