204 LearnersLast updated on May 26th, 2025
Divisibility Rule of 721
The divisibility rule is a way to find out whether a number is divisible by another number without using the division method. In real life, we can use the divisibility rule for quick math, dividing things evenly, and sorting things. In this topic, we will learn about the divisibility rule of 721.
What is the Divisibility Rule of 721?
The divisibility rule for 721 is a method by which we can find out if a number is divisible by 721 or not without using the division method.
Check whether 1442 is divisible by 721 with the divisibility rule.
Step 1: Multiply the last digit of the number by 2, here in 1442, 2 is the last digit. Multiply it by 2. 2 × 2 = 4
Step 2: Subtract the result from Step 1 from the remaining values but do not include the last digit. i.e., 144–4 = 140.
Step 3: As it is shown that 140 is not a multiple of 721, therefore, the number is not divisible by 721. If the result from step 2 is a multiple of 721, then the number is divisible by 721.
Tips and Tricks for Divisibility Rule of 721
Learning the divisibility rule will help kids to master division. Let’s learn a few tips and tricks for the divisibility rule of 721.
- Know the multiples of 721: Memorize the multiples of 721 (721, 1442, 2163, 2884, etc.) to quickly check the divisibility. If the result from the subtraction is a multiple of 721, then the number is divisible by 721.
- 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 721. For example: Check if 4326 is divisible by 721 using the divisibility test. Multiply the last digit by 2, i.e., 6 × 2 = 12. Subtract the remaining digits excluding the last digit by 12, 432–12 = 420. Still, 420 is not a multiple of 721, so 4326 is not divisible by 721.
- 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.
Common Mistakes and How to Avoid Them in Divisibility Rule of 721
The divisibility rule of 721 helps us quickly check if the given number is divisible by 721, but common mistakes like calculation errors lead to incorrect calculations. Here we will understand some common mistakes that will help you to understand.
Mistake 1
Not following the correct steps.
Students should follow the correct steps that are multiplying the last digit by 2 and then subtracting the result from the remaining digits excluding the last digit and checking whether it is a multiple of 721.
Mistake 2
Including the last digit in subtraction.
Students should keep in mind that they should exclude the last digit while subtracting and include all the remaining digits.
Mistake 3
Not repeating the process when the result is large.
Students often stop the process after they have got a large number to result in after subtraction. The process should be repeated until we get the smallest number that is divisible by 721.
Mistake 4
Not considering the negative values.
Students consider the negative values thinking divisibility rules don't apply to the negative values. But the divisibility rule is applicable for negative values too. So students should consider the negative values as positive while checking for divisibility.
Mistake 5
Confusing the steps
Students often confuse the steps or forget the steps. To avoid the error, students should practice regularly.
Divisibility Rule of 721 Examples
Problem 1
Is 4321 divisible by 721?
No, 4321 is not divisible by 721.
Explanation
To check if 4321 is divisible by 721, we need to apply the divisibility rule for 721. Imagine a rule where the last three digits are compared to the first digit.
1) The last three digits are 321.
2) The first digit is 4.
3) 4 is not equal to 321, so 4321 is not divisible by 721.
Problem 2
Check the divisibility rule of 721 for 1442.
No, 1442 is not divisible by 721.
Explanation
For checking divisibility by 721, consider a scenario where you need to compare certain parts of the number.
1) Take the first two digits: 14.
2) Take the last two digits: 42.
3) If 14 is not equal to 42, then 1442 is not divisible by 721.
Problem 3
Is 7210 divisible by 721?
Yes, 7210 is divisible by 721.
Explanation
Let's apply a hypothetical divisibility rule for 721.
1) Separate the number into 721 and 0.
2) The number 0 is clearly a remainder when divided by any non-zero number.
3) Thus, 7210 is divisible by 721.
Problem 4
Can 8649 be divisible by 721 following a divisibility rule?
No, 8649 is not divisible by 721.
Explanation
Apply a divisibility rule for 721 by using the following method:
1) Consider the number as two parts: 86 and 49.
2) The rule states that the two parts must be the same for divisibility.
3) Since 86 is not equal to 49, 8649 is not divisible by 721.
Problem 5
Check the divisibility rule of 721 for 1442 using a creative method.
No, 1442 is not divisible by 721.
Explanation
Imagine a creative rule for divisibility:
1) Separate the number into 14 and 42.
2) Check if the first part equals the last part.
3) Since 14 is not equal to 42, 1442 is not divisible by 721.
FAQs on Divisibility Rule of 721
1.What is the divisibility rule for 721?
2.How many numbers are there between 1 and 1000 that are divisible by 721?
3.Is 1442 divisible by 721?
4.What if I get 0 after subtracting?
5.Does the divisibility rule of 721 apply to all integers?
6.How can children in Oman use numbers in everyday life to understand Divisibility Rule of 721?
7.What are some fun ways kids in Oman can practice Divisibility Rule of 721 with numbers?
8.What role do numbers and Divisibility Rule of 721 play in helping children in Oman develop problem-solving skills?
9.How can families in Oman create number-rich environments to improve Divisibility Rule of 721 skills?
Important Glossaries for Divisibility Rule of 721
- 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 721 if the process described in the rule results in a multiple of 721.
- Multiples: Multiples are the results we get after multiplying a number by an integer. For example: multiples of 721 are 721, 1442, 2163, etc.
- Integers: Integers are the 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: Using the division method to confirm whether the result obtained from the divisibility rule is correct or not.
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About BrightChamps in Oman
Hiralee Lalitkumar Makwana
About the Author
Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.
Fun Fact
: She loves to read number jokes and games.
