Question

Possible Duplicate:
c# – How do I round a decimal value to 2 decimal places (for output on a page)

how to return decimal with long rest after the point like that:

3.786444499963

to this:

3.787

its not just cut the points it also round the rest of the number

Answer 1

But the generally accepted rounding of 3.786444499963 to three decimal places is 3.786. Why do you think otherwise?

Thus:

var round = Math.Round(3.786444499963m, 3, MidpointRounding.AwayFromZero);
Console.WriteLine(round == 3.786m); // prints true

If you want it to ALWAYS round up:

var round = Math.Round(3.786444499963m + 0.0005m, 3);
Console.WriteLine(round == 3.787m); // prints true

Do you see what I did there? I added 0.0005m to the input before using Math.Round. In general, to round x to n decimal places,

var round = Math.Round(x + 5m * Convert.ToDecimal(Math.Pow(10, -n - 1)), n);

Or, perhaps, to avoid the ugly double/decimal conversion:

int k = 1;
decimal value = 5m;
while(k <= n + 1) { value /= 10m; k++; }
var round = Math.Round(x + value, n);

There’s an edge case you need to be aware of. What happens to 3.786? Should it be rounded up to 3.787 or remain at 3.786? You haven’t specified what you want exactly, so I’ll leave this edge case to you.