# About calculations and conversion rules

Some studies use calculations and conversions. Calculations and conversions set the value of data items by performing calculations that use the value in one or more related items. You can perform calculations such as:

- Aging on date time data.
- Concatenations and other string manipulation.
- Arithmetic and analytical operations on numeric data.

Note: You cannot edit a calculation. To modify a calculation, you must delete the calculated report element and recalculate it.

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