10 LET A = 1
20 LET G = 1 / SQR(2)
30 GOSUB 60
40 PRINT A
50 STOP
60 LET T = A
70 LET A = (A + G) / 2
80 LET G = SQR(T * G)
90 IF A < T THEN 60
100 RETURN
110 END