The answer is 3333.
The digits of F are all the same. ✔ They all have same digit 3Â
The sum of all the digits of F is 12✔ 3+3+3+3=12Â
When any two of the digits are multiplied together, the answer is 9.✔ 3*3= 9Â
F is a four-digit number.✔ 3 3 3 3
  1 2 3 4
