To determine if a number is divisible by 3, you can follow a couple of simple methods that are easy to use and understand. Here’s a detailed explanation of these methods:
1. The Rule of Sum of Digits
The most common method to check for divisibility by 3 is to add up all the digits of the number.
For example, if we take the number 123:
- First, add the digits: 1 + 2 + 3 = 6
Since 6 is divisible by 3, it means that 123 is also divisible by 3.
You can apply this rule to any number. If the sum of the digits is divisible by 3, then the original number is divisible by 3.
2. Direct Division Method
If you prefer a more straightforward approach, you can also directly divide the number by 3.
For instance, if you want to check if 45 is divisible by 3:
- Divide 45 by 3: 45 ÷ 3 = 15
Since 15 is a whole number (with no remainder), we can conclude that 45 is divisible by 3.
3. Examples for Practice
Consider these examples:
- Example 1: Is 27 divisible by 3?
- Add the digits: 2 + 7 = 9. Since 9 is divisible by 3, 27 is also divisible by 3.
- Example 2: Is 50 divisible by 3?
- Add the digits: 5 + 0 = 5. Since 5 is not divisible by 3, 50 is not divisible by 3.
4. Conclusion
Using these methods, you can easily determine whether any given number is divisible by 3. The sum of its digits provides a quick check, while direct division gives an absolute answer. Remember, these techniques work for any size of number!