i already came up with this:
King has to stay between rooks, so the other pieces have to be between the king and a rook or behind a rook. This leads to a mathematical combination:
8 nCr 5= 8!/(3!*5!)=56
Now pieces are put in these 'slots' and taken in account that bishops and knights are double, we multiply this by:
5!/(2!*2!*1) or 5 nCr 2 * 3 nCr 2 *1 nCr 1=30
Still this leads to a number far greater than 960, i.e.:1680
This because I've forgotten the bishops who have to be on different-coloured squares. But how do I do that?