Divisibility Rule of 123

The divisibility rule for 123 is a method by which we can find out if a number is divisible by 123 or not without using the division method. Check whether 492 is divisible by 123 with the divisibility rule.

Step 1: Add the digits of the number together. For 492, add 4 + 9 + 2 = 15.

Step 2: Check if the sum obtained in Step 1 is divisible by 3. Since 15 is divisible by 3, the original number might be divisible by 123.

Step 3: Divide the original number by 123 to verify. 492 ÷ 123 = 4. As there is no remainder, 492 is divisible by 123.

Learning the divisibility rule will help kids to master division. Let’s learn a few tips and tricks for the divisibility rule of 123.

• Know the multiples of 123:
  Memorize the multiples of 123 (123, 246, 369, 492…etc.) to quickly check the divisibility. If the division of the original number by 123 results in a whole number, then the number is divisible by 123.

• Use estimation: If you find large numbers difficult, estimate the closest multiple of 123 and compare the difference. This can help in checking the divisibility quickly.

• Repeat the process for large numbers: Students should keep repeating the divisibility process with the sum of digits until they reach a small number that is easier to check for divisibility by 3. 
  
  For example: Check if 6153 is divisible by 123 using the divisibility test.
  
  Add the digits: 6 + 1 + 5 + 3 = 15.
  
  Since 15 is divisible by 3, check by division. 6153 ÷ 123 = 50. As there is no remainder, 6153 is divisible by 123.

• Use the division method to verify: Students can use the division method as a way to verify and crosscheck 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.

• Multiple: A multiple is the result of multiplying a number by an integer. For example, multiples of 123 are 123, 246, 369, 492, etc.

• Sum of digits: The result of adding all the digits in a number together. 

• Estimation: A method used to find an approximate answer, which can be useful in determining divisibility quickly.

• Verification: The process of confirming that a calculation or result is correct, often by using an alternate method such as division.