You can use hexadecimal numbers to pass a numeric(integer) value to a parameter in the RPG program when calling it from the command line.

Passing numeric value to a packed decimal numeric field in RPG:

CALL PGM(PGM1) PARM((x'0001F') (x'00010F'))

Here, the first parameter is a 3-length numeric field and passing value 1. The second parameter is a 4-length numeric field with and passing value of 10.

To pass a hexadecimal field you must start with x after X within quotes, there must be an even number of positions including the F.

So, passing value 1 to the numeric length 3 would be x’001F’ where F denotes a positive number and it is a signed bit. And as I remember we pass D for negative numbers.

However, passing value 10 to numeric length 4 is not x'0010F' since inside single quotes 0010F is an odd number of digits. So the correct value would be x'00010F i.e. add an extra zero in front of the number to make it an even number of positions within single quotes including F after X.

Just refer to some examples to understand it a little bit more,

1. If you trying to pass value 5.2 to the decimal (3,1) field and 543 value to the decimal (3) field.
   CALL PGM(PGM1) PARM((5.2) (543))
CALL PGM(PGM1) PARM((x'052F') (x'543F'))
2. If you trying to pass value 254674 to the numeric parameter of length 6 field.
   CALL PGM(PGM1) PARM((254674)
CALL PGM(PGM1) PARM((x'0254674F'))
   Add an extra 0 at the start of the number after x and within quotes so that to make it an even number of digits in the hex value being passed.

Passing 4-byte integer value to integer (10I) field field in RPG:
If you try to pass 1 and 10 respectively
CALL PGM(PGM1) PARM((x'00000001') (x'0000000A'))
Just refer to some other examples to understand it a little more:
Passing value for 3I and 5I and 10I and 20I parameters in RPG

1. passing value 10 to each 3I and 5I and 10I and 20I parameters in RPG
   CALL PGM(PGM1) PARM((X'0A') (X'000A') (X'0000000A') (X'000000000000000A'))
2. passing value 1 to each 3I and 5I and 10I and 20I parameters in RPG
   CALL PGM(PGM1) PARM((X'01') (X'0001') (X'00000001') (X'0000000000000001'))
3. passing value 18 to each 3I and 5I and 10I and 20I parameters in RPG
   CALL PGM(PGM1) PARM((X'12') (X'0012') (X'00000012') (X'0000000000000012'))

You can check convert decimal to hex value here.

Sample program
This is the sample program that you can create at your end and test the above calls for passing Integer values in 3I, 5I, 10I, and 20I parameters in the RPG program:

     D main            PR                  EXTPGM('PGM1') 
     D                                3I 0                      
     D                                5I 0                      
     D                               10I 0                      
     D                               20I 0                      
     D main            PI                                       
     D num1                           3I 0                      
     D num2                           5I 0                      
     D num3                          10I 0                      
     D num4                          20I 0                      
      /Free                                                     
           dsply num1;                                          
           dsply num2;                                          
           dsply num3;                                          
           dsply num4;                                          
                                                                
           *INLR  = *ON;                                        
      /End-Free