How to display the line number in cat command

The cat command returns the content of the file and the nl command adds also the line number. For example:

cat myfile.txt

this is the first line
this is the second line
and this is the third
this should be the forth

Now, if we want to get the line number too, we can run:

nl myfile.txt

     1  this is the first line
     2  this is the second line
     3  and this is the third
     4  this should be the forth

Another option is to use the cat command with the -n option such as:

cat -n myfile.txt

     1  this is the first line
     2  this is the second line
     3  and this is the third
     4  this should be the forth