How to add a trendline to a chart in Google Sheets?

To add a trendline to a chart in Google Sheets, you first need to create a chart:

1. Select the data range you want to include in your chart
2. Click on the 'Insert chart' button in the toolbar (it looks like a graph)
3. Select the chart type you want to use (line, column, scatter, etc.)
4. Customize the chart to your liking using the chart editor
5. Click anywhere on the chart to select it
6. In the toolbar, click on 'Chart editor'
7. Click on the 'Customize' tab (it looks like a paintbrush)
8. Scroll down to the 'Trendline' section and click the drop-down arrow
9. Select the type of trendline you want to use (linear, exponential, etc.)
10. Customize the trendline to your liking using the options available
11. Click 'Apply' to add the trendline to your chart

Adding a trendline to your chart can help you visualize trends and make predictions based on your data. It's a useful tool for anyone who works with data in Google Sheets.