Some presentations contain a ton of data that needs to be updated all the time. Quarterly results, LP updates of VC/PE funds, the latest sales data. Updating the numbers is time consuming and errors can easily sneak in (especially problematic with presentations to investors).
I do not recommend cutting and pasting Excel data into PowerPoint. You need serious PowerPoint skills to format the data correctly, and most spreadsheets are not build to present data, they are build to analyse it. Hence my approach of cutting the link between the spreadsheet and the presentation software, and creating a data chart from scratch, 100% focused on the audience, not the analyst.
How to deal with the updating?
I would suggest to create a special spreadsheet alongside your presentation. A new worksheet pulls the required numbers from the big "data dump" worksheet, rounds them up correctly. Place the numbers exactly as they should show up in your presentation slide. Now it is easy to update your presentation data. Add check sums to see whether percentages add up to 100%, and breakdowns go back to the total sales figure.
When the new quarter arrives, you over-write the data dump worksheet, and fix any broken/misplaced links.
Art: painting by Ivan Aivazovsky