Why does Math.Round(2.5) return 2 instead of 3?

Question

In C#, the result of Math.Round(2.5) is 2.

It is supposed to be 3, isn\'t it? Why is it 2 instead in C#?

Answer 1

Here's the way i had to work it around :

Public Function Round(number As Double, dec As Integer) As Double
    Dim decimalPowerOfTen = Math.Pow(10, dec)
    If CInt(number * decimalPowerOfTen) = Math.Round(number * decimalPowerOfTen, 2) Then
        Return Math.Round(number, 2, MidpointRounding.AwayFromZero)
    Else
        Return CInt(number * decimalPowerOfTen + 0.5) / 100
    End If
End Function

Trying with 1.905 with 2 decimals will give 1.91 as expected but Math.Round(1.905,2,MidpointRounding.AwayFromZero) gives 1.90! Math.Round method is absolutely inconsistent and unusable for most of the basics problems programmers may encounter. I have to check if (int) 1.905 * decimalPowerOfTen = Math.Round(number * decimalPowerOfTen, 2) cause i don not want to round up what should be round down.