thanks guy's

I was going for the following

636 was the running total of 10 samples minus the highest and lowest. That left 8 samples.

I therefore wanted to divide 636 by to get 79.5.

I ended up multiplying by 50 and diving by 4, then handle the digits either side of the decimal place (see example) it's work in progress, but welcome any pointers

Code:
temp_val[1] = 100                   ; real tempeture 10.0c
temp_val[2] = 115                   ; 11.5c
temp_val[3] = 122                   ; 12c etc...
temp_val[4] = 139
temp_val[5] = 150
temp_val[6] = 130
temp_val[7] = 80
temp_val[8] = 100
temp_val[9] = 115
temp_val[10] = 252

' total = 1301
' lowest = 8.0c
' highest = 25.2c
' middle 8 samples = 971
' average of the 8 sample = 121.1375 or 12.137c

;----[Main Program]---------------------------------------------------------
mainloop:

'index = 0
'index2 = 0

temp1[1] = 0
temp1[2] = 0
temp1[3] = 0

for index = 1 to 3 step 1                                   ; Take 10 sampels from 3 sensors

    For index2 = 1 to 10  step 1                            ; Take 10 reading
        
        IF index2 = 1 THEN
            temp_val_lo[index] = temp_val[1]                ; Set initial lowest reading to first reading
            temp_val_hi[index] = temp_val[1]                ; Set initial highest reading to first reading
        endif
                               
        LCDOUT $fe,1,"Sensor ",DEC index, " Data ",DEC index2
          
        if temp_val[index2] <= temp_val_lo[index] then      ; If readling lower than lowest
            temp_val_lo[index] = temp_val[index2]           ; Update lowest
                                                             
        elseif temp_val[index2] => temp_val_hi[index] then  ; If reading higher than highest
            temp_val_hi[index] = temp_val[index2]           ; Update highest
            
        ENDIF                                               ; Else reading is not highest or lowest and....
            temp1[index] = temp1[index] + temp_val[index2]  ; Add reading to running total
            
    next index2                                             ; Update next sample
         
        temp1[index] = temp1[index] - temp_val_hi[index]    ; Subtract the highest reading
                
        temp1[index] = temp1[index] - temp_val_lo[index]    ; Subtract the lowest reading
                        
        temp1[index] = (temp1[index] * 50)/4                ; Get rid of the decimal places

        LCDOUT $FE,1, "Sensor = ",DEC index
        LCDOUT $FE, $C0,"Temp = ",DEC temp1[index] DIG 4, DEC temp1[index] DIG 3,".", DEC temp1[index] dig 2, dec temp1[index] dig 1, dec temp1[index] Dig 0
        
        PAUSE 2000    
            
next index                                                  ; update next sensor

PAUse 5000

goto mainloop

End