CareerCup

Here you go. The algorithm is pretty neat, but recursive. I don't like the recursion, but - it should work well.

/*
Should be pretty neat, 
Taking a number and making it word by word 
Using recursion, next step - removing that  
*/
_names_ = [[1,'one'], [2,'two' ], [3,'three'],[ 4 , 'four' ] , [5,'five'] ,
          [6,'six'], [7,'seven' ], [8,'eight'],[ 9 , 'nine' ] , [10,'ten'],
          [11,'eleven'], [12,'twelve' ], [13,'thirteen'],[ 14 , 'fourteen' ] , [15,'fifteen'],
          [16,'sixteen'], [17,'seventeen' ], [18,'eighteen'],[ 19 , 'nineteen' ] ,
          [20,'twenty'], [30,'thirty'], [40,'forty'], [50,'fifty'], [60,'sixty'], [70,'seventy'],
          [80,'eighty'], [90,'ninety'], [100,'hundred'] , [1000, 'thousand' ] ,
          [ 1000000 , 'million' ], [1000000000, 'billion' ] , [1000000000000 , 'trillion' ] ]

_keys_ = dict( _names_ )          
def in_words( n ){
  if ( n == 0 ) return 'zero'
  // try to find the index of the item from the right side 
  // which has the property that division by that item > 0
  i = rindex( _names_ ) :: { (n / $.0 ) > 0 }
  // i would have the index , get result and reminder 
  res = (n / _names_[i][0] )
  rem = (n % _names_[i][0] )
  // recursion, string rep of result is given by ... 
  s_res = ( res @ _keys_ ) ? ( (res != 1 || n >=100 ) ? _keys_[res] : '' ) : in_words(res)
  // recursion, string rep of the reminder is given by ... 
  s_rem = ( rem @ _keys_ ) ? _keys_[rem] : (rem != 0 ? in_words(rem) : '' )
  // finally merge them, and we have our answer - careful not to merge empty strings 
  s_res + (empty(s_res)?'' : ' ')  + _names_[i][1] + (empty(s_rem)?'' : ' ') + s_rem
}

println( in_words(0) )
println( in_words(10) )
println( in_words(1012) )
println( in_words(983) )
println( in_words(87891729817981987) )
println( in_words(4312112121121) )

The results of course are:

zero
ten
one thousand twelve
nine hundred eighty three
eighty seven thousand eight hundred ninety one trillion seven hundred twenty nine billion eight hundred seventeen million nine hundred eigh
ty one thousand nine hundred eighty seven
four trillion three hundred twelve billion one hundred twelve million one hundred twenty one thousand one hundred twenty one

static void init(){
		
		map.put(0, "Zero");
		map.put(1, "One");
		map.put(2, "Two");
		map.put(3, "Three");
		map.put(4, "Four");
		map.put(5, "Five");
		map.put(6, "Six");
		map.put(7, "Seven");
		map.put(8, "Eight");
		map.put(9, "Nine");
		
		map.put(11, "Eleven");
		map.put(12, "Twelve");
		map.put(13, "Thirteen");
		map.put(14, "Fourteen");
		map.put(15, "Fifteen");
		map.put(16, "Sixteen");
		map.put(17, "Seventeen");
		map.put(18, "Eighteen");
		map.put(19, "Nineteen");
		
		map.put(10, "Ten");
		map.put(20, "Twenty");
		map.put(30, "Thirty");
		map.put(40, "Fourty");
		map.put(50, "Fifty");
		map.put(60, "Sixty");
		map.put(70, "Seventy");
		map.put(80, "Eightty");
		map.put(90, "Ninety");
		
		map.put(100, "Hundred and");
		map.put(1000, "Thousand");
		map.put(100000, "Lacks");
	}
	
	static String convert(int number, int divisor){
		
//		Single digit - return
		if(number < 10) { return map.get(number); }
		
//		Double digits
		if(number < 100) { return map.get(number - (number%10)) + " " + map.get(number%10); }
		
		while(number/ divisor > 9){
			divisor *= 10;
		}
		
		String currentString = "";
		if(!map.containsKey(divisor)){ currentString = map.get(Integer.valueOf(number/divisor + "0")); }
		else { currentString = map.get(number/divisor) + " " + map.get(divisor); }
		
		return currentString + " " + convert(number%divisor, 1);

	}

static void init(){
		
		map.put(0, "Zero");
		map.put(1, "One");
		map.put(2, "Two");
		map.put(3, "Three");
		map.put(4, "Four");
		map.put(5, "Five");
		map.put(6, "Six");
		map.put(7, "Seven");
		map.put(8, "Eight");
		map.put(9, "Nine");
		
		map.put(11, "Eleven");
		map.put(12, "Twelve");
		map.put(13, "Thirteen");
		map.put(14, "Fourteen");
		map.put(15, "Fifteen");
		map.put(16, "Sixteen");
		map.put(17, "Seventeen");
		map.put(18, "Eighteen");
		map.put(19, "Nineteen");
		
		map.put(10, "Ten");
		map.put(20, "Twenty");
		map.put(30, "Thirty");
		map.put(40, "Fourty");
		map.put(50, "Fifty");
		map.put(60, "Sixty");
		map.put(70, "Seventy");
		map.put(80, "Eightty");
		map.put(90, "Ninety");
		
		map.put(100, "Hundred and");
		map.put(1000, "Thousand");
		map.put(100000, "Lacks");
	}
	
	static String convert(int number, int divisor){
		
//		Single digit - return
		if(number < 10) { return map.get(number); }
		
//		Double digits
		if(number < 100) { return map.get(number - (number%10)) + " " + map.get(number%10); }
		
		while(number/ divisor > 9){
			divisor *= 10;
		}
		
		String currentString = "";
		if(!map.containsKey(divisor)){ currentString = map.get(Integer.valueOf(number/divisor + "0")); }
		else { currentString = map.get(number/divisor) + " " + map.get(divisor); }
		
		return currentString + " " + convert(number%divisor, 1);

	}