Divisibility Rule of 720

The divisibility rule for 720 is a method by which we can find out if a number is divisible by 720 or not without using the division method. To check whether a number is divisible by 720, we need to ensure that it is divisible by the prime factors of 720, which are 8, 9, and 5.

Step 1: Check divisibility by 8. A number is divisible by 8 if its last three digits form a number that is divisible by 8.

Step 2: Check divisibility by 9. A number is divisible by 9 if the sum of its digits is divisible by 9.

Step 3: Check divisibility by 5. A number is divisible by 5 if its last digit is 0 or 5.

Example: Check whether 1440 is divisible by 720 using the divisibility rule.

Step 1: Check divisibility by 8. The last three digits are 440. Since 440 is divisible by 8 (440 ÷ 8 = 55), the number passes this check.

Step 2: Check divisibility by 9. The sum of the digits of 1440 is 1+4+4+0=9, which is divisible by 9, so the number passes this check.

Step 3: Check divisibility by 5. The last digit of 1440 is 0, which is divisible by 5, so the number passes this check.

Since 1440 passes all three checks, it is divisible by 720.

Learning the divisibility rule will help kids to master division. Let’s learn a few tips and tricks for the divisibility rule of 720.

• Know the prime factors: Memorize the prime factors of 720 (8, 9, and 5) to quickly check the divisibility.
   
• Use the sum of digits: For checking divisibility by 9, quickly add the digits and see if the sum is divisible by 9.
   
• Use the last digits: For checking divisibility by 8 and 5, focus on the last three digits and the last digit respectively.
   
• Repeat the process for large numbers: For very large numbers, break them down into smaller components to check divisibility by 8, 9, and 5 separately.
   
• Use the division method to verify: Use long division if needed to verify and cross-check results.

• 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 an even number.
   
• Prime factors: The prime numbers that multiply together to give the original number. For 720, these are 2, 3, and 5.
   
• Multiples: The results we get after multiplying a number by an integer. For example, multiples of 720 are 720, 1440, 2160, etc.
   
• Integers: Numbers that include all whole numbers, negative numbers, and zero.
   
• Sum of digits: The total obtained by adding all the digits of a number together. This is used for checking divisibility by 9.