As you expalin in your question total deduction is based on unpaidleaves/4 also you mention you are using Math.Floor to get exact value.
it may works if you implement the same logic which you explain.
Please refer the Sample code as per the question requirement . It may help you.
<body>
<form id="form1" runat="server">
<div>
<span id="lblCalculation" runat="server"></span>
</div>
</div>
</form>
</body>
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
Dim totalLeave As String = String.Empty
Dim i As Integer = 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
i += 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
i += 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
i += 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
i += 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
i += 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
i += 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
i += 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
i += 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
i += 1
totalLeave = totalLeave & String.Format("total leaves day {0} => deduct {1} day <br/>", i, Me.Totaldeduction(i))
lblCalculation.InnerHtml = totalLeave
End Sub
Private Function Totaldeduction(unpaidleaves As Double) As Integer
Return Convert.ToInt32(Math.Floor(unpaidleaves / 4))
End Function