how many 4 letter words can we make from "A", "B", "C" each letter should come at least once.

and also please give a generic formula to calculate if the letters are increased.. like 5,6,7..

• #include
  
  long binomial_coefficient(int k, int i)
  {
  unsigned long fact1, fact2;
  
  if (i==0)
  return 1;
  
  for (fact1=1, fact2=1;i>0; k--,i--)
  {
  fact1 = fact1*k;
  fact2 = fact2*i;
  }
  return fact1/fact2;
  
  }
  
  long power(int base, int power)
  {
  long result = 1;
  
  for(;power>0;power--)
  result = result * base;
  
  return result;
  }
  
  int main()
  {
  int i, sum=0;
  int n = 3; // Number of letters
  int length = 4; // Length of the word
  // Derived formula
  for(i=0;i
• 7 years agoHelpfull: Yes(0) No(1)