18. Find the next term: 2, 6, 12, 20, 30, ?
Explanation: The differences are: 4, 6, 8, 10... (increasing by 2). So the next difference is 12. 30 + 12 = 42. Alternatively, the series is n(n+1): 1×2, 2×3, 3×4, 4×5, 5×6, 6×7=42.
Explanation: The differences are: 4, 6, 8, 10... (increasing by 2). So the next difference is 12. 30 + 12 = 42. Alternatively, the series is n(n+1): 1×2, 2×3, 3×4, 4×5, 5×6, 6×7=42.