A is a hundred. B is ten. C is a unit.

In this number, C(3)(5)=60.

A has three numbers of 60/5= 12. Similarly, there are other numbers like 12.

B has three digits of 60/5- 12, and the rest are the same.

So the sum of these three digits =12× (200+300+400+700+900)+12× (20+30+40+70+90)+12× (2+3+)

= 12×(2500+250+25)

=33300

Extended data:

Combination is one of the important concepts in mathematics. Taking out M different elements (0≤m≤n) from N different elements at a time and synthesizing a group regardless of their order is called selecting the combination of M elements from N elements without repetition.

Combination with repetition is a special combination. You can repeatedly select m elements from n different elements. Synthesizing a group of m elements called n elements regardless of their order is a repeatable combination. Two repeated combinations are the same if and only if the elements are the same and the same elements are taken the same times.