Look at this series: 7, 10, 8, 11, 9, 12, ... What number should come next?

Given data

• Series: 7, 10, 8, 11, 9, 12, ...

Concept/Approach
Two interleaved sequences:

• Odd positions: 7, 8, 9, ... (increase by 1)
• Even positions: 10, 11, 12, ... (increase by 1)

Step-by-Step calculation
Positions 1–6 given → next is position 7 (odd subsequence): 7, 8, 9, 10 ...

Verification/Alternative
Pattern holds if we list pairs: (7,10), (8,11), (9,12), next pair starts with 10.

Common pitfalls

• Adding 3 then subtracting 2 alternately; that fails at later terms.

Final Answer
10