In Microsoft Excel, you can assign datatypes to columns of data. The Microsoft Excel datatypes are ODBC datatypes. PowerCenter supports ODBC datatypes and converts them to transformation datatypes. If you do not assign datatypes in Microsoft Excel, the Designer imports each column as VARCHAR. If you want to perform numeric or aggregate calculations in a mapping, assign numeric datatypes in Microsoft Excel before importing the spreadsheet.
To format columns in Microsoft Excel:
Open the Microsoft Excel file.
Select the columns of data that consist of numeric data.