Hi Nav,
Take a look at this link:
Creating Data Driven Pages—Help | ArcGIS for Desktop
Scroll down to the section about data driven scale:
When using point features, if you want to use only one map scale for each page, choose the Center and Maintain Current Scale option. Then, after exiting the Setup Data Driven Pages dialog box, set the scale of the Detail Data Frame to the scale you want. If you want different scales for different point features, you need to use a field containing these values and select Data Driven Scale on the Extent tab and choose this field. You cannot use a layer from another data frame, another map document, or a stand-alone layer file (.lyr) as an index layer. The index layer must be a feature layer. You cannot use raster-based layers as the index layer. |
I hope this segment is useful.
Well... maybe scroll down further:
Data Driven Scale
By choosing the Data Driven Scale option, the map scale of the detail data frame for each page in the Data Driven Pages series is data driven. Use the drop-down list to select an appropriate field containing the data you want to use to determine scale. The drop-down list is filtered to display applicable field types. These include short integer, long integer, float, and double. When you specify a Data Driven Scale field, values from this field define the map scale of the detail data frame for each page in the Data Driven Pages series. If a value is null, Data Driven Pages uses the scale value of the previous page. Any fixed scale or a fixed extent associated with the detail data frame is ignored when Data Driven Pages are enabled. |
There are other helpful resources in the document regarding scale, etc.
