Excel column titles can be considered as a number representing system with base as 26

where A=1, B=2..., Z=26.

```
public int titleToNumber(String s) {
if(s==null || s.equals("")) return 0;
int counter=0;
int column=0;
for(int i=s.length()-1;i>-1;i--,counter++){
// similar to what we do when we convert number from binary to decimal
column+= Math.pow(26,counter) * ((int)s.charAt(i) - 64);
}
return column;
}
```