Divisibility Rule of 99

The divisibility rule for 99 is a method by which we can find out if a number is divisible by 99 or not without using the division method. Check whether 297 is divisible by 99 with the divisibility rule.

Step 1: Check if the given number is divisible by both 9 and 11. First, check divisibility by 9: Add all the digits of the number. For 297, 2+9+7=18, which is divisible by 9.

Step 2: Next, check divisibility by 11: Alternately subtract and add the digits of the number. For 297, calculate 2-9+7=0, which is divisible by 11.

Step 3: Since 297 is divisible by both 9 and 11, it is divisible by 99.
 

Learning the divisibility rule will help kids to master division. Let’s learn a few tips and tricks for the divisibility rule of 99.

• Know the multiples of 99: Memorize the multiples of 99 (99, 198, 297, 396...etc.) to quickly check the divisibility. If the result from the checks shows divisibility by both 9 and 11, then the number is divisible by 99.
   
• Use the divisibility rules for 9 and 11: Familiarize yourself with the divisibility rules for 9 (sum of digits is divisible by 9) and 11 (alternating sum of digits is divisible by 11) to make the process easier.
   
• Repeat the process for large numbers: Students should keep repeating the divisibility process for both 9 and 11 until they confirm divisibility by 99. For example, check if 594 is divisible by 99. 5+9+4=18 (divisible by 9), and 5-9+4=0 (divisible by 11). Hence, 594 is divisible by 99.
   
• 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. For example, a number is divisible by 2 if it ends with an even number.
   
• Multiples: Multiples are the results we get after multiplying a number by an integer. For example, multiples of 99 are 99, 198, 297, etc.
   
• Alternating sum: The process of alternately subtracting and adding digits of a number to determine divisibility by 11.
   
• Integer: A whole number that can be positive, negative, or zero.
   
• Verification: The process of confirming a result by using a different method, such as division, to ensure accuracy.