The burndown prediction in Hansoft is calculated using a weighted average.
This manual page will explain which calculations Hansoft preform to determine the "Predicted velocity" in a burndown chart.
You can customize prediction settings in the "Customize project..." dialog.
This example will use a sprint prediction of "3 days weighted average".
Weekends and holidays
The first thing to be aware of is that Hansoft ignores "Free days" such as holidays and weekends when predicting velocity.
Weekends are easy to identify by their darker shade of gray in the timeline.
The equation would then look something like this when we add values: