Creating Your First Multidimensional Cube - Getting Started with SQL Server 2012 Cube Development - page 75

the Fact Internet Sales Count measure residing under the Fact Internet
Sales measure group and choose Properties .
9. In the Properties window, you can control how the measure should be cal-
culated through the AggregateFunction property. You can also change
the DataType of the measure, this can be necessary to change when you
have measures that use the DistinctCount or Count aggregate to avoid
overflow of your data. If you have measures that may overflow and that use
the Sum aggregation, then you have to ensure that they do not overflow by
casting to a bigger data type in the data source view. Find the FormatString
property, as you can see by the drop-down list here you can control the
format of the measure.