# Question

Formatted question description: https://leetcode.ca/all/171.html

```
171 Excel Sheet Column Number
Given a column title as appear in an Excel sheet, return its corresponding column number.
For example:
A -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28
...
Example 1:
Input: "A"
Output: 1
Example 2:
Input: "AB"
Output: 28
Example 3:
Input: "ZY"
Output: 701 (26*26+25)
```

# Algorithm

It is equivalent to a problem of converting from hexadecimal to decimal. It is not difficult, as long as the conversion is bit by bit.

# Code

Java