Question: I am new to LINUX. This question sounds simple and stupid, but I suppose this has a lot of meaning behind it. "HOW COMMANDS ARE PROCESSED IN LINUX?". Which means suppose if I give ls command,what makes it to display list of all files inside the directory?. I have been searching for the answer, and I could not find any clear explanation for the same. Please help me to solve the same.

Answer: 
The simplest option would probably be to use `String.replaceAll`:

```
text = text.replaceAll("[0.]*$", "");

```

The `$` makes sure it's only trimming the end of the string.

Note that if you start with "0" you'll end up with an empty string - think about what you want the result to be in that situation.
well - this is simple but a compute-intesiv solution...

```
String str = "8320987112741390144276341183223364380754172606361245952449277696409600000000000000";
System.out.println(str);
int count = 0;
char c = '0';
do {
    c = str.charAt(str.length()-1);
    if (c == '0' ){
        str = str.substring(0, str.length() - 1);
        count ++;
    }
}while(c == '0' );
System.out.println(str);
System.out.println("amount:"+amount);

```

but it's a very obvious solution... (just remove last zero...until there is no more...)