How to add days to an existing date value
To create a column that displays date values that are greater than the date values in another column, complete the following steps.
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Select a column. From the context menu, choose ColumnChoose New Computed Column. New Computed Column appears.
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Validate the expression and choose OK. The calculated column appears in the report. For every value in the Order Date column, the calculated column displays a date seven days later than the order date.

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