let showPrintMessage daysPassed = 
    let name = match abs(daysPassed) % 100 with
               | y when y >= 5 && y <= 20 -> "дней"
               | _ -> match abs(daysPassed) % 10 with
                      | 1 -> "день"
                      | 2 | 3 | 4 -> "дня"
                      | _ -> "дней"
    "Событие наступит через " + string daysPassed + " " + name + "!"

[1..30] |> List.map showPrintMessage