# 168. Excel Sheet Column Title

#### Easy

***

Given an integer `columnNumber`, return *its corresponding column title as it appears in an Excel sheet*.

For example:

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

 

**Example 1:**

```
Input: columnNumber = 1
Output: "A"
```

**Example 2:**

```
Input: columnNumber = 28
Output: "AB"
```

**Example 3:**

```
Input: columnNumber = 701
Output: "ZY"
```

 

**Constraints:**

* `1 <= columnNumber <= 231 - 1`

```python
class Solution:
    def convertToTitle(self, columnNumber: int) -> str:
        if columnNumber == 0:
            return ""
        else:
            # Why -1 here , think using 'A' character it will be clear
            return self.convertToTitle((columnNumber-1)//26) + chr((columnNumber-1) % 26 + ord('A'))
```