10 REM PI calculator 
20 LET P = 0 
30 LET Q = 0 
40 LET R = 0 
50 LET S = 0 
60 LET T = 0 
70 LET D = 1 
80 LET Z = 2 
90 PAGE
99 PRINT "ATN SOLUTION IS" 
100 PRINT 4 * ATN(1) 
110 FOR C = 1 TO 1000 
120 	LET T = S 
130	LET S = R 
140	LET R = Q 
150 	LET Q = P 
160 	LET P = P + 1/D 
170 	LET Z = -Z 
180  	LET D = Z - D 
190 NEXT C
199 PRINT "ITERATED SOLUTION IS"
200 PRINT (P + 4*(Q+S) + 6*R + T)/4
300 END
