You will produce a short, elegant, recursive algorithm that spells out any number between 1 and 2.1 billion.

Allow the user to input a number in the range from 1 to 2.1 billion (a positive 32-bit int), then spell out the number (e.g. 123456 would output "one hundred twenty three thousand four hundred fifty six").

Use a recursive method "say(n)" where say(n) returns the string corresponding to the input integer n.