What is the sum of all of the four-digit positive integers that can be written with the digits 1, 2, 3 and 4 if each digit must be used exactly once in each four-digit positive integer?
The sum is (1 + 2 + 3 + 4)*1111*8 = 88880.
There are 4! =24 such numbers:
1234 , 1243 , 1324 , 1342 , 1423 , 1432 , 2134 , 2143 , 2314 , 2341 , 2413 , 2431 , 3124 , 3142 , 3214 , 3241 , 3412 , 3421 , 4123 , 4132 , 4213 , 4231 , 4312 , 4321 >>Total = 66,660 - Their total sum
