ArcGIS Go to Scale Tool
Go to Scale Tool/textbox
/* This code snippet gets the new scale from the textbox control object to calculate the zoom factor. It also calculates the map center as a web adf point and supplies that to the Map.Zoom method to change the scale appropriately.*/
protected void Text_Scale_TextChanged(object sender, EventArgs e)
{
double xmin = Map1.Extent.XMin;
double ymin = Map1.Extent.YMin;
double currentEnvelopewidth = Map1.Extent.Width;
double currentEnvelopeHeight = Map1.Extent.Height;
double currentMapCenterX = xmin + (currentEnvelopewidth / 2);
double currentMapCenterY = ymin + (currentEnvelopeHeight / 2);
double zoomfactor = 1;
System.Web.UI.WebControls.TextBox tb = (System.Web.UI.WebControls.TextBox)sender;
double newscale = Convert.ToDouble(tb.Text);
zoomfactor = mapOriginalScale / newscale;
ESRI.ArcGIS.ADF.Web.Geometry.Point adfPoint = new ESRI.ArcGIS.ADF.Web.Geometry.Point();
adfPoint.X = currentMapCenterX;
adfPoint.Y = currentMapCenterY;
Map1.Zoom(zoomfactor, adfPoint);
}