10 CLS
20 PRINT "LINEAR INTERPOLATION"
30 DEFDBL A-Z 
40 PRINT 
50 PRINT "X,Y OF FIRST POINT"; 
60 INPUT X1,Y1 
70 PRINT "X,Y OF SECOND POINT"; 
80 INPUT X2,Y2 
90 PRINT "INTERPOLATE: X ="; 
100 INPUT X 
110 Y=Y1+(Y2-Y1)/(X2-X1)*(X-X1)
120 PRINT "             Y = ";INT(Y*1000+.5)/1000
130 PRINT 
140 PRINT "MORE POINTS ON THIS LINE? (1=YES, 0=NO)"; 
150 INPUT Z 
160 PRINT 
170 IF Z=1 THEN 90   
180 PRINT "NEW LINE? (1=YES, 0=N0)"; 
190 INPUT Z 
200 IF Z=1 THEN 40   
210 END