Converting Days into Human Readable Duration Text

let divmod n m = n / m, n % m

let units = [
    ("Centuries", TimeSpan.TicksPerDay * 365L * 100L );
    ("Years", TimeSpan.TicksPerDay * 365L);
    ("Weeks", TimeSpan.TicksPerDay * 7L);
    ("Days", TimeSpan.TicksPerDay)
]

let duration days =
    let rec duration' ticks units acc =
        match units with
        | [] -> acc
        | (u::us) ->
            let (wholeUnits, ticksRemaining) = divmod ticks (snd u)
            duration' ticksRemaining us (((fst u), wholeUnits) :: acc)
    duration' (TimeSpan.FromDays(float days).Ticks) units []

String.Format("{0} Weeks, {1} days", days / 7, days % 7);

public class UnitOfMeasure {
		public UnitOfMeasure(string name, int value) {
			Name = name;
			Value = value;
		}

		public string Name { get; set; }
		public int Value { get; set; }

		public static UnitOfMeasure[] All = new UnitOfMeasure[] {
			new UnitOfMeasure("Year", 356),
			new UnitOfMeasure("Month", 30),
			new UnitOfMeasure("Week", 7),
			new UnitOfMeasure("Day", 1)
		};

		public static string ConvertToDuration(int days) {
			List<string> results = new List<string>();

			for (int i = 0; i < All.Length; i++) {
				int count = days / All[i].Value;

				if (count >= 1) {
					results.Add((count + " " + All[i].Name) + (count == 1 ? string.Empty : "s"));
					days -= count * All[i].Value;
				}
			}

			return string.Join(", ", results.ToArray());
		}
	}

#light
let conversions = [|
    365, "Year", "Years"
    30, "Month", "Months"
    7, "Week", "Weeks"
    1, "Day", "Days" |]
let ToDuration numDays =
    conversions
    |> Array.fold_left (fun (remainDays,results) (n,sing,plur) ->
        let count = remainDays / n
        if count >= 1 then
            remainDays - (count * n),
              (sprintf "%d %s" count (if count=1 then sing else plur)) :: results
        else
            remainDays, results
    ) (numDays,[])
    |> snd |> (fun rs -> System.String.Join(", ", List.rev rs |> List.to_array))
printfn "%s" (ToDuration 1008)