Which of the following numbers are divisible by 3?
505,550

Answer

To determine whether the numbers 505 and 550 are divisible by 3, we will use the divisibility rule for 3, which states that a number is divisible by 3 if the sum of its digits is divisible by 3.

### Step-by-Step Solution:

1. **Identify the numbers**: We have two numbers to check: 505 and 550.

2. **Calculate the sum of the digits of 505**:
- The digits of 505 are 5, 0, and 5.
- Sum = 5 + 0 + 5 = 10.

3. **Check if 10 is divisible by 3**:
- To check divisibility, we see if 10 can be divided by 3 without a remainder.
- 10 ÷ 3 = 3 with a remainder of 1.
- Since there is a remainder, 10 is not divisible by 3.

4. **Conclusion for 505**: Therefore, 505 is **not divisible by 3**.

5. **Calculate the sum of the digits of 550**:
- The digits of 550 are 5, 5, and 0.
- Sum = 5 + 5 + 0 = 10.

6. **Check if 10 is divisible by 3** (same as above):
- 10 ÷ 3 = 3 with a remainder of 1.
- Since there is a remainder, 10 is not divisible by 3.

7. **Conclusion for 550**: Therefore, 550 is **not divisible by 3**.

### Final Answer:
Neither 505 nor 550 is divisible by 3.