Dim Days, Years As Integer

        'get Days
        Days = Ticks * (1 / 24) * (1 / 60) * (1 / 60) 'Ticks = Seconds from Year 1, January 1

        'get years by counting up from the beginning
        Years = 0
        While True
            'if leap year
            If (Year Mod 4 = 0) AndAlso (Year Mod 100 <> 0) OrElse (Year Mod 400 = 0) Then
                If Days >= 366 Then 'if we have enough days left to increment the year
                    Years += 1
                    Days -= 366
                Else
                    Exit While
                End If
                'if not leap  year
            Else
                If Days >= 365 Then 'if we have enough days left to increment the year
                    Years += 1
                    Days -= 365
                Else
                    Exit While
                End If
            End If
        End While

        Return Years

Const TICKS_PER_YEAR As Long = 315360000000000
Function YearsSinceBeginningOfTimeUntil(ByVal d As DateTime) As Integer
    Return Math.Floor(d.Ticks / TICKS_PER_YEAR)
End Function

let dateFrom = new DateTime(1,1,1)

let dateTo = dateFrom.AddSeconds(100000000.0)

let yearsSince dateFrom dateTo =
    let intRepresentation (date: DateTime) =
        date.ToString"yyyy.MMdd" |> Convert.ToDouble

    let dateToNum = intRepresentation dateTo
    let dateFromNum = intRepresentation dateFrom

    int (dateToNum - dateFromNum)

yearsSince dateFrom dateTo |> Dump

let dob = DateTime(1985, 4, 16)

let calculateAge = yearsSince dob

calculateAge DateTime.Today |> Dump

Sub GetDateFromSerial(ByVal dateSerial As ULong, ByRef year As Long, ByRef month As Integer, ByRef dayOfMonth As Integer, ByRef secondsIntoDay As Integer, ByRef asString As String)
    Const SecondsInOneDay As ULong = 86400 ' 24 hours * 60 minutes per hour * 60 seconds per minute

    'Dim startOfGregorianCalendar As DateTime = New DateTime(1582, 10, 15)
    'Dim startOfGregorianCalendarInSeconds As ULong = (startOfGregorianCalendar - New DateTime(1, 1, 1)).TotalSeconds

    Const StartOfGregorianCalendarInSeconds As ULong = 49916304000

    secondsIntoDay = dateSerial Mod SecondsInOneDay

    If dateSerial < StartOfGregorianCalendarInSeconds Then
        year = -1
        month = -1
        dayOfMonth = -1

        Dim days As Integer = (StartOfGregorianCalendarInSeconds - dateSerial) \ SecondsInOneDay

        asString = days & IIf(days = 1," day"," days") &" before the adoption of the Gregorian calendar on October 15, 1582"
    Else
        'Dim maximumDateValueInSeconds As ULong = (DateTime.MaxValue - New DateTime(1, 1, 1)).TotalSeconds
        Const MaximumDateValueInSeconds As ULong = 315537897600

        If dateSerial <= MaximumDateValueInSeconds Then
            Dim parsedDate As DateTime = DateTime.MinValue.AddSeconds(dateSerial)

            year = parsedDate.Year
            month = parsedDate.Month
            dayOfMonth = parsedDate.Day
        Else
            ' Move the date back into the range that DateTime can parse, by stripping away blocks of
            ' 400 years. Aim to put the date within the range of years 2001 to 2400.
            Dim dateSerialInDays As ULong = dateSerial \ SecondsInOneDay

            Const DaysInFourHundredYears As Integer = 365 * 400 + 97 ' Three multiple-of-4 years in each 400 are not leap years.

            Dim fourHundredYearBlocks As Integer = dateSerialInDays \ DaysInFourHundredYears

            Dim blocksToFactorInLater As Integer = fourHundredYearBlocks - 5

            Dim translatedDateSerialInDays As ULong = dateSerialInDays - blocksToFactorInLater * CLng(DaysInFourHundredYears)

            ' Parse the date as normal now.
            Dim parsedDate As DateTime = DateTime.MinValue.AddDays(translatedDateSerialInDays)

            year = parsedDate.Year
            month = parsedDate.Month
            dayOfMonth = parsedDate.Day

            ' Factor back in the years we took out earlier.
            year += blocksToFactorInLater * 400L
        End If

        asString = New DateTime(2000, month, dayOfMonth).ToString("dd MMM") &"," & year
    End If
End Sub

Function GetSerialFromDate(ByVal year As Long, ByVal month As Integer, ByVal dayOfMonth As Integer, ByVal secondsIntoDay As Integer) As ULong
    Const SecondsInOneDay As Integer = 86400 ' 24 hours * 60 minutes per hour * 60 seconds per minute

    If (year < 1582) Or _
       ((year = 1582) And (month < 10)) Or _
       ((year = 1582) And (month = 10) And (dayOfMonth < 15)) Then
        Throw New Exception("The specified date value has no meaning because it falls before the point at which the Gregorian calendar was adopted.")
    End If

    ' Use DateTime for what we can -- which is years prior to 9999 -- and then factor the remaining years
    ' in. We do this by translating the date back by blocks of 400 years (which are always the same length,
    ' even factoring in leap years), and then factoring them back in after the fact.

    Dim fourHundredYearBlocks As Integer = year \ 400

    Dim blocksToFactorInLater As Integer = fourHundredYearBlocks - 5

    If blocksToFactorInLater < 0 Then blocksToFactorInLater = 0

    year = year - blocksToFactorInLater * 400L

    Dim dateValue As DateTime = New DateTime(year, month, dayOfMonth)

    Dim translatedDateSerialInDays As ULong = (dateValue - New DateTime(1, 1, 1)).TotalDays

    Const DaysInFourHundredYears As ULong = 365 * 400 + 97 ' Three multiple-of-4 years in each 400 are not leap years.

    Dim dateSerialInDays As ULong = translatedDateSerialInDays + blocksToFactorInLater * DaysInFourHundredYears

    Dim dateSerial As ULong = dateSerialInDays * SecondsInOneDay + secondsIntoDay

    Return dateSerial
End Function

function foo(seconds):
  count = seconds
  year = 0
  while (count > 0):
    if leap_year(year)
      count = count - 366
    else
      count = count - 365
    year ++
  return year