Option Explicit
Sub test()
Dim x As Integer, y As Byte, i As Byte, j As Byte, k As Byte
y = Range("A3:A" & Range("A65536").End(xlUp).Row).Rows.Count
x = WorksheetFunction.RoundUp(y / 8, 0)
k = 3
For i = 4 To 12
For j = 1 To x
Cells(k, 3).Value = i
Cells(k, 4).Value = MonthName(i)
Cells(k, 5).Value = Cells(k, 3).Value - Cells(k, 2).Value
k = k + 1
If k = y + 3 Then GoTo fin
Next j
If i = 7 Then i = 8
Next i
fin:
Range("E3:E" & Range("E65536").End(xlUp).Row).NumberFormat = "0.00"" mois"""
End Sub