Steven Parker173,522 Points
The program says to type "done", but it's really looking for "quit".
So "done" just causes an invalid number conversion (and then crashes).
Some other hints:
- in addition to the total, you will probably want to keep a count of entered numbers in the loop
- when the loop ends, you can then divide the total by the count to get the average
- the symbol for a divide operation is a slash ("
- you can then use WriteLine to show that average, much like you already show the total