There are several examples in the coursework about how to modify words for the Genitive, but they are not completely consistent. (to me anyway)
From the main Grammar page:
der → (masculine) Das Auto des Vaters. (des + s)
das → (neuter) Das Fahrrad des Kindes." (des + es)
However in the exercise: “Paul ist gestresst: A1 ▹ Unit 26”
“der Mann” becomes “des Mannes” <- masculine but unlike the grammar page there is an added “e”.
Also, these examples show “das Kind” becoming “des Kindes”, however other places “das Hotel” becomes “des Hotels” <- neuter, but no added “e”.
Any help? The differences here are not explained anywhere I can find so far.