The triangular numbers are 1, 3, 6, 10, … The next one is A12 B14 C15 D16 Tap an answer to check. Show the answer Answer: C. 15 Add 2, 3, 4, then 5: 10 + 5 = 15. Report a problem The answer is wrong Spelling or typing mistake The question is unclear Out of date Something else Send
