📐 Mathematics · Permutations and Combinations · JEE

The sum of all 4-digit numbers formed using each of 1, 2, 3, 4 exactly once is:

Answer: 66660.

Correct answer: A. 66660

Explanation: Each digit occupies each place 3! = 6 times; digit sum = 10. Sum = 6·10·1111 = 66660.

Counting tree for selecting 2 items from {A, B, C} without repetition: 3 x 2 = 6 ordered arrangements.

Concept context

Counting, arrangements, and selections