HKIMO 2020 Grade 6 National Final (Heat) Set 01 Question 24

Andy climbs a 10-step staircase, moving 1,2 or 3 steps at a time. Steps 5 and 8 are broken and cannot be landed on. How many ways can he reach the top?

Source glossary (English–Vietnamese): Go up: đi lên; Step: bậc thang; How many: có bao nhiêu; Destroyed: bị phá hủy.