5 PRINT "ENTER VALUE OF X. (TO END PROGRAM INPUT 99999)"
10 INPUT A 
12 IF A=99999 THEN 90
15 PRINT 
20 PRINT " X","DIFFERENCE QUOTIENT" 
25 D=0  
30 FOR N=1 TO 10 
35 D1=D
40 X=A+.5^N 
45 D=(FNC(X)-FNC(A))/(X-A)  
50 PRINT INT(X*1E4+.5)/1E4,D 
55 NEXT N 
60 PRINT 
65 PRINT "DERIVATIVE AT X=";A;"IS:";2*D-D1 
70 PRINT 
80 PRINT "ENTER VALUE OF X" 
85 GOTO 10  
90 END 

