To determine if a number is divisible by 3, you can use a simple rule: add up all the digits of the number, and if the sum is divisible by 3, then the original number is also divisible by 3.
For example, let’s take the number 123. Add the digits together: 1 + 2 + 3 = 6. Since 6 is divisible by 3, we can conclude that 123 is also divisible by 3.
This method works because of how numbers are structured in our decimal system. Each digit’s place value contributes a factor of 10, which itself is not relevant for divisibility by 3. Therefore, it’s only the sum of the digits that matters.
Another example is the number 456. Adding the digits: 4 + 5 + 6 = 15. Since 15 is divisible by 3, so is 456.
In contrast, if we take the number 124, adding the digits gives us 1 + 2 + 4 = 7. Since 7 is not divisible by 3, we can say that 124 is also not divisible by 3.
This method is handy and quick, allowing anyone to check for divisibility by 3 without complicated calculations!