I will be grateful if anyone provide me the idea to solve the following problem. The problem says, we have five digits a, b, c, d, e (0 <= a, b, c, d, e <= 9). Now for these five digits, we can convert each of 120 permutations(5!=120) of these five digits into a decimal number. if the sum of all the 120 numbers is x, then we can exclude a number N from the sum which results in a sum of 119 numbers. Now we will be given that sum of 119 numbers, we have to find the numbers N that we excluded. if multiple answers possible output them all in ascending order. Note : the initial five numbers will not be provided. Problem Link