Combination applications extend beyond simple selection. Conditional combinations: Select with restrictions (e.g., at least 1 specific person). Approach: (1) Total combinations; (2) Subtract those violating condition. Example: Select 3 from 5 people including person A. Total = C(5,3) = 10. Without A = C(4,3) = 4. Including A = 10 - 4 = 6. Complementary counting: Use for negation problems. Distribution problems: Distribute identical items into distinct groups (stars and bars method). Example: Distribute 5 identical balls into 3 boxes = C(5+3-1, 3-1) = C(7,2) = 21. Exam tip: Identify restriction type. Use complementary counting when 'at least' or 'exclude' phrasing. Practice: Multi-condition problems.