To be clear, tutorialspoint uses Open Object Rexx not Regina!
/* Main program
The below program is used to add numbers
Call the add function */
add(500000000000,6000000000000000000000)
exit
add:
parse arg a,b
say a + b
The output of the above program will be −
6.00000000E+21
but Regina matches tutorialspoint answer, but also got an error…
bill@bill-MS-7B79:~/MyStuff/Rexx$ regina prog03.rexx
6.00000000E+21
4 +++ add(500000000000,6000000000000000000000)
Error 44 running "/home/bill/MyStuff/Rexx/prog03.rexx", line 4: Function did not return data
Error 44.1: No data returned from function "ADD"
bill@bill-MS-7B79:~/MyStuff/Rexx$