hi
simple, in the amount box you put (your stake amount)+(IF(total_won<0,-total_won,0)/(back_price-1))
the - in front if the total_won is important and the capital IF
this will bet say 5€ plus any losses you have
so bet 5 win, total won = 4.75 (won at 2.0)
next 5 loss, total won = -.25
next 5+.25/odds
mcbee