I need more than 32 classes when classifying a raster in arcmap 10. I tried manually typing in the number i need, but it doesn't seem possible. This is key in proceding with my project. Is this do-able?
In the future please provide more details on your problem. Vague questions yield vague or incorrect answers and irritate forum members.
What I can draw from your question your are actually referring to rendering raster symbology and not an isocluster or supervised classification. Whereas the dropdown box provides a maximum of 32 classes, if you click on the "classify" radio button you can manually enter the number of classes you want. This symbology will be honored if you want to assign these class breaks using the "Arctoolbox > Spatial Analyst > Reclass > Reclassify" tool to create a new integer raster.
The software default for maximum number of raster classes in an integer raster is 200. If you want to change this you need to use the "AdvancedArcMapSettings.exe" utility located in the "Utilities" directory in the ArcGIS install path. Under the raster tab you can change the maximum number of classes.