125. Formation of integers. Can the reader name the sum of all integers formed from the four digits $1,2,3,4$? In other words, it is required to calculate the sum of such numbers as $1234,1423,4312$, etc. Of course, one could write down all such numbers in a row and then add them up. However, it is more interesting to find a simple rule that can be used to find the sums of numbers formed from four different arbitrarily chosen (non-zero) digits.