If in each number, all the odd digit is added by 1 and all the even digit is added by 2 then, which of the following will be the lowest number after mentioned operation?

Correct Answer: 372

To find which number becomes the lowest after performing the given operations, let us apply the rules step-by-step to each digit of every given number.

Rules for modification:
1. If a digit is odd, add 1 to it.
2. If a digit is even, add 2 to it.

Let us process each option one by one:

1. For 619:
- 6 is even → 6 + 2 = 8
- 1 is odd → 1 + 1 = 2
- 9 is odd → 9 + 1 = 10 (or digit becomes 0, but treating digit-wise addition: 8, 2, 10)
Applying the operation digit-by-digit: 619 becomes 8210 (or looking at the first digit 8, it starts with 8).

2. For 574:
- 5 is odd → 5 + 1 = 6
- 7 is odd → 7 + 1 = 8
- 4 is even → 4 + 2 = 6
So, 574 becomes 686.

3. For 372:
- 3 is odd → 3 + 1 = 4
- 7 is odd → 7 + 1 = 8
- 2 is even → 2 + 2 = 4
So, 372 becomes 484.

4. For 471:
- 4 is even → 4 + 2 = 6
- 7 is odd → 7 + 1 = 8
- 1 is odd → 1 + 1 = 2
So, 471 becomes 682.

5. For 453:
- 4 is even → 4 + 2 = 6
- 5 is odd → 5 + 1 = 6
- 3 is odd → 3 + 1 = 4
So, 453 becomes 664.

Now, let us compare the resulting numbers:
- 619 → 8210
- 574 → 686
- 372 → 484
- 471 → 682
- 453 → 664

Comparing these new numbers (484, 664, 682, 686, 8210), the lowest number obtained is 484, which corresponds to the original number 372.

Therefore, 372 will be the lowest number after the operation.