Get last (ie endswith) 3 digits of a decimal (.NET)

Question

I may be using Math for evil... But, in a number written as 0.7000123 I need to get the "123" - That is, I need to extract the last 3 digits in the decimal portion of a number. The least significant digits, when the first few are what most people require.

Examples:

0.7500123 -> 123  
0.5150111 -> 111

It always starts from digit 5. And yes, I'm storing secret information inside this number, in the part of the decimal that will not affect how the number is used - which is the potentially evil part. But it's still the best way around a certain problem I have.

I'm wondering whether math or string manipulation is the least dodgy way of doing this.

Performance is not an issue, at all, since I'm calling it once.

Can anyone see an easy mathematical way of doing this? eg A combination of Math functions (I've missed) in .NET?

Answer 1

It's a strange request to be sure. But one way to get an int value of the last 3 digits is like so:

int x = (int)((yourNumber * 10000000) % 1000);

I'm going to guess there's a better way to get the information you're looking for that's cleaner, but given what you've asked for, this should work.

Answer 2

First Convert Your number into the String.

string s = num.ToString();


string s1 =  s.Substring(s.Length - 3, 3);

Now s1 Contains Last 3 Digits Of the Number