C programming: Input Number and return the number name

I started programming recently, and a teacher of programming called a C program that allows the user to place a digit and in return receive the number of name, example:

input: 5 output: Five

I tried to do with a switch but the program fail when i use more the 1 digit, example:

input: 20 output (expected): twenty output (given): two zero

Right now I'm out of ideas, so I would ask for some tips to guide me, if anyone has any idea how to do, I appreciate the help