Concept:
For 3-digit permutations, each digit appears equally in hundreds, tens, and units places.
Explanation:
Digits = 2, 3, 5
Sum of digits:
\[
2 + 3 + 5 = 10
\]
Each digit appears:
\[
(3-1)! = 2 \text{ times in each place}
\]
Total sum:
\[
2 \times (100 + 10 + 1) \times 10
\]
\[
= 2 \times 111 \times 10 = 2220
\]