5 DEFINT A-Z
10 INPUT "Number:";A
15 IF A=0 THEN GOTO 50
20 GOSUB 1000
30 PRINT "Square root ";A;"=";B
40 GOTO 10
50 END
60 REM ------------------------------
1000 REM       SQUARE ROOT ROUTINE. RETURNS ROOT OF A IN 
1010 REM       B. WORKSPACE IS C AND D.
1020 IF A>1 GOTO 1050
1030 B = 1 
1040 RETURN
1050 B = A\182 + 2
1060 D = 0 
1070 C = (B + A\B)\2
1074 REM CHECK IF C SHOULD BE ROUNDED UP 
1075 IF (A - A\(2*B)*B*2)>B THEN C = C + 1
1080 IF B = C THEN RETURN
1085 REM CHECK FOR OSCILLATION OF RESULT
1090 IF (B-C) = D GOTO 1130 
1100 D = C-B
1110 B = C 
1120 GOTO 1070
1130 REM PICK THE LARGER OF B OR C THEN RETURN
1140 IF B>C RETURN
1150 B = C
1160 RETURN