Reasoning – Series Completion
What is Series Completion?
These questions test your ability to identify and continue patterns in sequences of numbers, letters, or symbols. The key is to understand the logic behind the progression.
Types of Series
1. Arithmetic Series: Addition or subtraction by a fixed number.
2. Geometric Series: Multiplying/dividing by a fixed number.
3. Square/Cube Series: Squares (1, 4, 9...) or cubes (1, 8, 27...)
4. Alternating Series: Different operations in alternate steps.
5. Complex/Mixed Series: Combines multiple patterns (e.g., +2, ×2 alternately).
Example Questions
- 2, 4, 8, 16, ?
Answer: 32 (×2 pattern)
- 1, 4, 9, 16, ?
Answer: 25 (Perfect squares)
- A, C, F, J, ?
Answer: O (+2, +3, +4, ...)
- Z, X, U, Q, ?
Answer: L (−2, −3, −4, ...)
Exam Tips
- Always write down the differences between consecutive terms to find patterns.
- Be patient; complex patterns may alternate or involve reverse logic.
- Check for combination of arithmetic and geometric logic, especially when numbers increase or decrease rapidly.
- Use tables or notations to visualize letter shifts.
Common Mistakes
- Not considering alternate term patterns.
- Missing composite rules like ‘+2 then ×2’.
- Guessing based on visual similarity rather than actual rule.
Quick Revision Checklist
- Practice separate types: arithmetic, geometric, alphabets.
- Memorize squares and cubes up to 20.
- Be comfortable converting letters to their alphabetical positions (A=1, B=2...).
- Use ruled paper or grid to keep calculations clean during timed practice.
Summary: Series Completion helps in developing predictive reasoning. It’s a valuable skill not only in exams but in coding, analytics, and logical tasks requiring sequence detection and pattern-based decision-making.