Dreieinhalbfache
... is German for a multiple of 3,5 (externer Link)
The German word "Dreieinhalbfache" actually means that you should multiply something three times and then add half of that something to the result. Here is an example:
Das Dreieinhalbfache von 8:
3 times 8 is 24. Then add half 8.
The final result then is 28.