Divisibility Rule of 399

The divisibility rule for 399 is a method by which we can find out if a number is divisible by 399 or not without using the division method. Check whether 798 is divisible by 399 with the divisibility rule.

Step 1: Notice that 399 can be broken down into its factors, which are 3, 7, and 19. A number is divisible by 399 if it is divisible by each of these factors.

Step 2: Check divisibility by 3. Add the digits of the number: 7 + 9 + 8 = 24. Since 24 is divisible by 3, 798 is divisible by 3.

Step 3: Check divisibility by 7 using the known rule for 7. Double the last digit, 8 × 2 = 16, and subtract it from the rest of the number, 79. So, 79 - 16 = 63. Since 63 is divisible by 7, 798 is divisible by 7.

Step 4: Check divisibility by 19. This is usually done by direct division or using divisibility tests if known. Divide 798 by 19. If it results in an integer, it is divisible. 798 ÷ 19 = 42, which is an integer.

Since 798 is divisible by 3, 7, and 19, it is divisible by 399.

Learn the divisibility rule to help master division. Let’s learn a few tips and tricks for the divisibility rule of 399.

Know the factors of 399: Memorize that 399 = 3 × 7 × 19. A number must be divisible by all these factors to be divisible by 399.

Use quick checks for factors: Use simple tricks for 3, 7, and 19 to check divisibility quickly, such as the sum of digits for 3 or direct division for 19.

Repeat the process for large numbers: If a number is large, break it down into smaller parts or directly check each factor.

Use the division method to verify: After using divisibility checks, verify by dividing the number by 399 for accuracy.
 

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

• Factors: Numbers that multiply together to give another number. For 399, these are 3, 7, and 19.

• Multiples: The results we get after multiplying a number by an integer. For instance, 798 is a multiple of 399.

• Integer: A whole number that can be positive, negative, or zero.

• Verification: The process of confirming results, often by using direct division to check accuracy.