Explanation:

Given Information:
- The sum of the digits in a three-digit number is 12.
- When the digits are reversed, the number is increased by 495.

Let's Break it Down:

Step 1: Understanding the Digits
- Let the three-digit number be represented as ABC, where A, B, and C are the digits.
- According to the given information, we have A + B + C = 12.

Step 2: Reversing the Digits
- When the digits are reversed, the new number becomes 100C + 10B + A.
- The difference between the original number (100A + 10B + C) and the reversed number (100C + 10B + A) is 495.
- This can be represented as (100C + 10B + A) - (100A + 10B + C) = 495.

Step 3: Solving the Equations
- Substituting A + B + C = 12 into the equation (100C + 10B + A) - (100A + 10B + C) = 495, we get 99C - 99A = 495.
- Simplifying further, we have C - A = 5.

Step 4: Finding the Numbers
- Since C - A = 5, the possible combinations for (A, C) are (2, 7) or (3, 8).
- However, the sum of the digits is 12, so the correct combination is (3, 8).
- Therefore, the original number is 382 and the reversed number is 827.

Conclusion:
- The original three-digit number is 382, and when its digits are reversed, the number becomes 827, which is 495 more than the original number.