Divisibility Rule of 391

The divisibility rule for 391 is a method by which we can find out if a number is divisible by 391 or not without using the division method. Check whether 782 is divisible by 391 with the divisibility rule.

 
Step 1: Since 391 does not have a simple divisibility rule like smaller numbers, we will need to rely on the known properties or factors of 391. Note that 391 = 17 × 23. 

Step 2: Check if the number is divisible by both 17 and 23. If 782 is divisible by both, then it is divisible by 391. 

Step 3: For 17, divide 782 by 17. 782 ÷ 17 = 46, which is an integer, so 782 is divisible by 17. Now check for 23. 782 ÷ 23 = 34, which is also an integer, so 782 is divisible by 23.

Step 4: Since 782 is divisible by both 17 and 23, it is also divisible by 391.

Learning divisibility rules will help you master division. Let’s learn a few tips and tricks for the divisibility rule of 391.

• Know the factors of 391: Memorize the factors of 391 (17 and 23) to quickly check the divisibility. If a number is divisible by both factors, it is divisible by 391.
   
• Use the factor method: Break down the number into its prime factors and check divisibility with each factor.
   
• Repeat the process for large numbers: For larger numbers, verify divisibility by both 17 and 23 using the factor method described.
   
• Use the division method to verify: You can use the division method to verify and crosscheck results. This will help verify and also learn.
   
• Practice with examples: Regular practice with examples will help avoid common mistakes.

• Divisibility Rule: The set of rules used to determine whether a number is divisible by another number.
   
• Factors: Numbers that divide another number completely without leaving a remainder. For 391, these are 17 and 23.
   
• Prime Numbers: Numbers greater than 1 that have no divisors other than 1 and themselves. 17 and 23 are prime numbers.
   
• Integer: A whole number that can be positive, negative, or zero.
   
• Remainder: The number left over after division when a number does not divide another number exactly.