REM Rosetta Code task: 'Calculate the integer value of 5^(4^(3^2))'
      REM https://rosettacode.org/wiki/Arbitrary-precision_integers_(included)
      
      ON ERROR IF ERR=17 CHAIN @lib$ + "../examples/tools/touchide" ELSE \
      \                  MODE 7 : REPORT : PRINT : END
      
      INSTALL @lib$ + "bigint" : REM library supplied with the language
      
      OSCLI "FONT """ + @lib$ + "DejaVuSans"", 36"
      VDU 5,30,10
      PRINT "Calculating ";
      
      FOR power% = 5 TO 2 STEP -1
        PRINT ;power%;
        OSCLI "FONT """ + @lib$ + "DejaVuSans"", " + STR$(power% * 6)
        MOVE BY 0, power% * 6
      NEXT
      
      OSCLI "FONT """ + @lib$ + "DejaVuSansMono"", 19"
      PRINT '''
      
      ON TIME PRINT "."; : RETURN
      t1 = TIME
      x = FNbignew(200000) : REM set maximum number of digits in result
      PROCbigval(x, "5")
      PROCbigpow(x, x, 4^(3^2))
      x$ = FNbigstr(x)
      t2 = TIME
      ON TIME OFF
      
      PRINT '
      PRINT "Total number of decimal digits: "; LEN(x$)
      PRINT
      PRINT "First twenty digits: " LEFT$(x$, 20)
      PRINT " Last twenty digits: " RIGHT$(x$, 20)
      PRINT
      PRINT "Approximate run time: "; (t2 - t1) / 100 " seconds"
      
      REPEAT WAIT 4 : UNTIL FALSE