Divisibility Rule of 191

The divisibility rule for 191 is a method by which we can find out if a number is divisible by 191 or not without using the division method. Check whether 5731 is divisible by 191 with the divisibility rule.

Step 1: Multiply the last digit of the number by 2, here in 5731, 1 is the last digit. Multiply it by 2. 1 × 2 = 2.

Step 2: Subtract the result from Step 1 from the remaining values but do not include the last digit. i.e., 573–2 = 571.

Step 3: As it is shown that 571 is not a multiple of 191, therefore, the number is not divisible by 191. If the result from step 2 is a multiple of 191, then the number is divisible by 191.

Learning divisibility rules will help kids to master division. Let’s learn a few tips and tricks for the divisibility rule of 191.

• Know the multiples of 191: Memorize the multiples of 191 (191, 382, 573, 764, etc.) to quickly check the divisibility. If the result from the subtraction is a multiple of 191, then the number is divisible by 191.

• Use negative numbers: If the result we get after the subtraction is negative, we will avoid the symbol and consider it as positive for checking the divisibility of a number.

• Repeat the process for large numbers: Students should keep repeating the divisibility process until they reach a small number that is easily verifiable.

For example: Check if 7652 is divisible by 191 using the divisibility test. Multiply the last digit by 2, i.e., 2 × 2 = 4. Subtract the remaining digits excluding the last digit by 4, 765–4 = 761. Repeat the process: 1 × 2 = 2. Now, subtract 2 from 76, 76–2 = 74. Since 74 is not a multiple of 191, 7652 is not divisible by 191.

• Use the division method to verify: Students can use the division method as a way to verify and cross-check their results. This will help them to verify and also learn.

• Divisibility rule: The set of rules used to find out whether a number is divisible by another number or not.

• Multiples: Multiples are the results we get after multiplying a number by an integer. For example, multiples of 191 are 191, 382, 573, 764, etc.

• Integers: Integers are numbers that include all the whole numbers, negative numbers, and zero.

• Subtraction: Subtraction is a process of finding out the difference between two numbers by reducing one number from another.

• Verification: Verification is the process of confirming the accuracy of a result, often using an alternative method like division.