Divisibility Rule of 3

The divisibility rule for 3 is a method by which we can find out if a number is divisible by 3 or not without using the division method. Check whether 123 is divisible by 3 with the divisibility rule.  

Step 1: Add up all the digits of the number. In 123, the digits are 1, 2, and 3, so add them: 1 + 2 + 3 = 6.  

Step 2: Check if the result from Step 1 is a multiple of 3. Since 6 is a multiple of 3, 123 is divisible by 3. If the sum is not a multiple of 3, then the number isn't divisible by 3.

Learn divisibility rules to help kids master division. Let’s learn a few tips and tricks for the divisibility rule of 3.

 
Know the multiples of 3:

Memorize the multiples of 3 (3, 6, 9, 12, 15, etc.) to quickly check the divisibility. If the sum of the digits is a multiple of 3, then the number is divisible by 3.  

Repeat the process for large numbers:

Students should keep repeating the divisibility process until they reach a small number that is easily recognized as a multiple of 3. For example, check if 1947 is divisible by 3 using the divisibility test. Add the digits: 1 + 9 + 4 + 7 = 21. Since 21 is a multiple of 3, 1947 is divisible by 3.

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. For example, a number is divisible by 3 if the sum of its digits is a multiple of 3.

• Multiples: Multiples are the results we get after multiplying a number by an integer. For example, multiples of 3 are 3, 6, 9, 12, etc.

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

• Sum: The result of adding numbers together. For the divisibility rule of 3, it involves adding all the digits of a number.

• Verify: To confirm the accuracy through another method, such as using division to check the result obtained from the divisibility rule.