Excel 2016 added a good new feature: One-click forecasting to help you understand current trends and predict future ones. Here's how it operates.

First you will need a table containing a number of dates or times and values associated with those dates. For instance, weekly stock values or monthly sales data. Excel will use these values to create a new worksheet with a forecast chart.

Select any cell in one of the series. Excel will automatically choose the rest of the data for you in the next step.
Go to the Data tab and click Forecast Sheet.
(Optional) Adjust the forecast end date in the forecast worksheet preview.
(Optional) Click the Options menu and adjust the forecasting options.
Click Create.

In some moments, you'll find a new sheet in your workbook containing the forecast chart based on your historical data. In that sheet, Excel will even produce a tablet containing the historical and predicted values, which you'll modify if you'd like to adjust the forecast.