A letter series is a sequence of letters that follows a specific logical rule or pattern.
The challenge is to decipher the underlying rule and determine the missing letter(s) or the next letter(s) in the sequence. These letter sequences follow particular patterns to challenge candidates to figure out the hidden logic behind them and describe a possible future event following the next letters.

The logical Series patterns can differ, including any order, number-based positions in the alphabet, sequences, or changes based on letter positions.
Types of Letter Series Patterns
1. Alphabetical Order Patterns
- Simple Forward/Backward Series:
Example:
A, B, C, D, ? (Next: E)
Z, Y, X, W, ? (Next: V)
- Skip Pattern (Fixed Intervals):
Example:
A, D, G, J, ? (Skip 2 letters: A→B,C→D)
B, E, H, K, ? (Next: N)
2. Position-Based Patterns
- Letter Position in Alphabet (A=1, B=2, etc.):
Example:
D (4), H (8), L (12), P (16), ? (Next: T=20)
- Mathematical Operations on Positions:
Example:
C (3), F (6), I (9), L (12), ? (Next: O=15)
3. Reverse Alphabet Patterns
- Reverse Position (Z=1, Y=2, ..., A=26):
Example:
V (5), R (9), N (14), ? (Next: J=19)
4. Repetition and Alternation Patterns
A, B, A, C, A, D, ? (Next: A)
X, Y, Z, X, Y, Z, ? (Next: X)
Tips to Solve Letter Series Reasoning
Following are the tips through which a candidate can solve the letter series reasoning questions easily for any competitive and placement exams.
- Write all alphabet letters on a rough paper.
- Try to find the difference between 2 successive word or an alphabet
- Find the difference between 2 pattern
- Add that difference before the missing pattern. That will be the missing pattern
Also Check:
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