The sum of all 4 digit numbers that can be formed by using the digits 2, 4, 6, 8 (repetition of digits not allowed) is

As in last question sum of the digits in the unit place 6 (2 + 4 + 6 + 8) = 120 units. Similarly sum of digits in ten place in 120 tens and in hundredth place is 120 hundreds etc. Sum of all the 24 numbers is 120 (1 + 10 + ${10}^2$ + ${10}^3$ ) = 120 X 1111 = 133320.