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# Excel Column Number InterviewBit Solution

Problem Description:

Given a column title A as appears in an Excel sheet, return its corresponding column number.

Problem Constraints

`1 <= |A| <= 100`

Input Format

`First and only argument is string A.`

Output Format

`Return an integer`

Example Input

```Input 1:
1

Input 2:
28```

Example Output

```Output 1:
"A"

Output 2:
"AB" ```

Example Explanation

```Explanation 1:
1 -> "A"

Explanation 2:
A  -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28 ```

## Approach

This question is about base conversion, just think what would you have done if you have given a binary (base-2) instead of base-26.

## Time & Space Complexity:

`Time Complexity: O(N) `

- N is the size of the string.

`Space Complexity: O(1)`

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