Divisibility Rule of 87

The divisibility rule for 87 is a method by which we can find out if a number is divisible by 87 or not without using the division method. Check whether 1044 is divisible by 87 with the divisibility rule.  

Step 1: Multiply the last digit of the number by 5, here in 1044, 4 is the last digit, multiply it by 5. 4 × 5 = 20 

Step 2: Subtract the result from Step 1 from the remaining values but do not include the last digit. i.e., 104–20 = 84.

Step 3: As it is shown that 84 is not a multiple of 87, therefore, the number is not divisible by 87. If the result from Step 2 is a multiple of 87, then the number is divisible by 87.

Learning the divisibility rule will help kids master division. Let’s learn a few tips and tricks for the divisibility rule of 87.

• Know the multiples of 87:  Memorize the multiples of 87 (87, 174, 261, 348…etc.) to quickly check the divisibility. If the result from the subtraction is a multiple of 87, then the number is divisible by 87. 
   
• Use the 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 divisible by 87.  
  
  For example: Check if 3483 is divisible by 87 using the divisibility test.  Multiply the last digit by 5, i.e., 3 × 5 = 15. Subtract the remaining digits excluding the last digit by 15, 348–15 = 333. Still, 333 is a large number, hence we will repeat the process again and multiply the last digit by 5, 3 × 5 = 15.  
  
  Now subtracting 15 from the remaining numbers excluding the last digit, 33–15 = 18.  As 18 is not a multiple of 87, 3483 is not divisible by 87. 
   
• 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 the number ends with even numbers.
   
• Multiples: Multiples are the results we get after multiplying a number by an integer. For example, multiples of 87 are 87, 174, 261, 348, 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: The process of confirming that a result is correct, such as using division to verify results obtained from a divisibility rule.