Maths Playing with Numbers part 8 (Divisibility Test : 3 , 9) CBSE Class 8 Mathematics VIII

TL;DR

Learn how to determine if a number is divisible by 3, 7, or 9 using the sum of its digits.

Transcript

hello friends this video on playing the numbers part 8 is brought to you by example calm no more fear from exam now it is look at divisibility by 3 now this is more interesting because in this case we look we do not look at the last digit or the last digit here we basically look at the sum of the digits so a number is divisible by 3 is the sum of t... Read More

Key Insights

• 🍹 Divisibility by 3 is determined by the sum of the digits of a number.
• 🍹 Divisibility by 7 can also be checked using the sum of digits rule.
• 🍹 Divisibility by 9 is determined by the sum of the digits as well.
• 🍹 The sum of digits rule applies to both small and large numbers.
• ⌛ This method of checking divisibility saves time compared to traditional division.
• 📏 The distributive property is used to explain the reasoning behind the divisibility rule.
• 📏 The rule applies to any number, regardless of its size or complexity.

Questions & Answers

Q: How can you determine if a number is divisible by 3?

To check divisibility by 3, add up the digits of the number. If the sum is divisible by 3, then the number is divisible by 3.

Q: What is the rule for determining if a number is divisible by 7?

To check divisibility by 7, add up the digits of the number. If the sum is divisible by 7, then the number is divisible by 7.

Q: How can the divisibility rule be applied to determine if a number is divisible by 9?

For divisibility by 9, add up the digits of the number. If the sum is divisible by 9, then the number is divisible by 9.

Q: Are there any exceptions to the sum of digits rule for divisibility?

No, there are no exceptions. The sum of digits rule is always applicable whether the number is small or large.

Summary & Key Takeaways

• Divisibility by 3: A number is divisible by 3 if the sum of its digits is a multiple of 3.

• Divisibility by 7: Use the sum of digits rule to check if the number is divisible by 7.

• Divisibility by 9: If the sum of the digits is divisible by 9, then the number is divisible by 9.