[assembly] Printing out a number in assembly language?

Have you tried int 21h service 2? DL is the character to print.

mov dl,'A' ; print 'A'
mov ah,2
int 21h

To print the integer value, you'll have to write a loop to decompose the integer to individual characters. If you're okay with printing the value in hex, this is pretty trivial.

If you can't rely on DOS services, you might also be able to use the BIOS int 10h with AL set to 0Eh or 0Ah.