There are plenty of multiplication examples about - and the PICList isn't restricted in any way, simply cut and paste the code off the screen?.

If you like I can post the maths routines I always use?, they are about to appear in my next tutorial (interfacing a Dallas DS1620 temperature sensor).

Quick edit, here are the routines I use!.

Code:

;16 bit Maths subroutines
Sub16:
       		COMF   Acc2H, f       		; Take two's complement
		COMF   Acc2L, f       		; of Acc2. If zero, Acc2L
		INCF   Acc2L, f
		BTFSC  STATUS, Z   		; overflowed, so carry
		INCF   Acc2H, f       		; into Acc2H.
Add16:
       		BCF    Flags, OverFlow 		; clear overflow flag
		MOVF   Acc2L, w    		; Add the LSBs. If carry,
		ADDWF  Acc1L, f
		BTFSC  STATUS, C   		; increment MSB of sum.
		INCF   Acc1H, f
		MOVF   Acc2H, w   		; Add the MSBs
		ADDWF  Acc1H, f
		BTFSC  STATUS, C   		; check for sum overflow
		BSF    Flags, OverFlow 		; set overflow flag
		MOVF   Acc1L, w    		; return lobyte in W
		RETURN
Mult16:
		CLRF   Acc3H          		; Clear product to make
		CLRF   Acc3L         		; way for new calculation.
		MOVLW  d'16'        		; Number of bits to calc.
		MOVWF  tmp1
Multiply_loop
		BCF    STATUS, C
		RLF    Acc3L, f        		; Shift product left.
		RLF    Acc3H, f
		BCF    STATUS, C
		RLF    Acc1L, f        		; Shift multiplicand left.
		RLF    Acc1H, f
		BTFSS  STATUS, C    		; If carry, add multiplier
		GOTO   Multiply_skip
		MOVF   Acc2L, w      		; to the product. Else skip.
		ADDWF  Acc3L, f
		BTFSC  STATUS, C    		; 16-bit addition: prod+mulp
		INCF   Acc3H, f
		MOVF   Acc2H, w
		ADDWF  Acc3H, f
Multiply_skip
		DECFSZ tmp1
		GOTO   Multiply_loop
		MOVF   Acc3H, w
		MOVWF  Acc1H        		; return answer in Acc1
		MOVF   Acc3L, w
		MOVWF  Acc1L        		; with lobyte in W
		RETURN

DIV16:          MOVF    Acc2H, w                ; Check for division by 0.
		IORWF   Acc2L, w
		BTFSC   STATUS, Z
		RETLW   d'255'        		; Error code= 255: return.
		MOVLW   d'1'          		; Otherwise, initialize variables
		MOVWF   tmp1
		CLRF    tmp2         		; index for the division.
		CLRF    Acc3H
		CLRF    Acc3L
Divide_sh_loop  BTFSC   Acc2H, d'7'   		; Shift divisor left
		GOTO    Divide_d1
		BCF     STATUS, C     		; until msb is in
		RLF     Acc2L, f         	; Acc2H.7.
		RLF     Acc2H, f         	; tmp1 = no. of shifts+1.
		INCF    tmp1
		GOTO    Divide_sh_loop
Divide_d1       BCF     STATUS, C
		RLF     Acc3L, f          	; Shift quotient left.
		RLF     Acc3H, f
		MOVF    Acc2L,w       		; top = top - btm.
		SUBWF   Acc1L, f
		BTFSC   STATUS, C     		; If top - btm < 0 then
		GOTO    Divide_d2
		MOVLW   d'1'          		; top = top + btm
		SUBWF   Acc1H, f
		BTFSC   STATUS, C     		; The idea is to do the
		GOTO    Divide_d2
		INCF    Acc1H, f         	; the subtraction and comparison
		MOVF    Acc2L, w      		; (top > btm?) in one step.
		ADDWF   Acc1L, f
		goto    Divide_reentr 		; Then, if btm > top, undo <Microchip instruction>
Divide_d2       MOVF    Acc2H, w      		; the subtraction by adding
		SUBWF   Acc1H, f
		BTFSS   STATUS, C     		; top and btm back together
		goto    Divide_less   		; <Microchip instruction>
		BSF     Acc3L,  d'0'
Divide_reentr
		BCF     STATUS, C
		RRF     Acc2H, f
		RRF     Acc2L, f
		DECFSZ  tmp1
		GOTO    Divide_d1
		MOVF    Acc3H, w
		MOVWF   Acc1H         		; return answer in Acc1
		MOVF    Acc3L, w
		MOVWF   Acc1L        		; with lobyte in W
		RETURN
Divide_less     MOVF    Acc2L, w      		; btm > top, so
		ADDWF   Acc1L, f
		BTFSC   STATUS, C     		; undo the subtraction by
		INCF    Acc1H, f         	; adding them back together.
		MOVF    Acc2H, w
		ADDWF   Acc1H, f
		goto    Divide_reentr 		; <Microchip instruction>

SHIFTR:         MOVWF    Acc2L
_LoopR          BCF      STATUS, C
		RRF      Acc1H, F
		RRF      Acc1L, F
		DECFSZ   Acc2L
		GOTO     _LoopR
		MOVF     Acc1L, W
		RETURN

SHIFTL:         MOVWF    Acc2L
_LoopL          BCF      STATUS, C
		RLF      Acc1L, F
		RLF      Acc1H, F
		DECFSZ   Acc2L
		GOTO     _LoopL
		MOVF     Acc1L, W
		RETURN