Format Number like Stack Overflow (rounded to thousands with K suffix)

Question

How to format numbers like SO with C#?

10, 5k, ...

Answer 1

Like this: (EDIT: Tested)

static string FormatNumber(int num) {
    if (num >= 100000)
        return FormatNumber(num / 1000) + "K";
    if (num >= 10000) {
        return (num / 1000D).ToString("0.#") + "K";
    }
    return num.ToString("#,0");
}

Examples:

• 1 => 1
• 23 => 23
• 136 => 136
• 6968 => 6,968
• 23067 => 23.1K
• 133031 => 133K

Note that this will give strange values for numbers >= 10⁸.
For example, 12345678 becomes 12.3KK.