You may want to use a bar chart that automatically updates based on information when it is updated in a spreadsheet, such as financial information.
In Excel, highlight the data you want to use in your chart. Select Insert>Chart. The wizard takes you through a number of steps. On Step 4, you can select a different sheet to put the chart on if you don't want it to be on the same page as the data.
After you've created the chart, select Edit>Copy from the menu bar to copy it.
Open PowerPoint. Select Edit>Paste Special.
The Paste Special dialog box opens. Choose the Paste Link option, which will display a list that includes Microsoft Chart Object. Make sure that is selected and choose OK. Now, when you open the presentation, it will ask you if you want to update the links.