Which of the following does not fit in the letter number series?

Answer: JR6 does not fit the pattern.

Pattern: For the items that fit, the difference between the alphabetical positions of the second letter and the first letter equals the given number plus 1.

• DG2: D = 4, G = 7 → difference = 3 = 2 + 1

• EK5: E = 5, K = 11 → difference = 6 = 5 + 1

• JR6: J = 10, R = 18 → difference = 8, but 6 + 1 = 7, so the gap does not match the number

• PY8: P = 16, Y = 25 → difference = 9 = 8 + 1

Therefore JR6 is the odd one out because its letter difference (8) does not equal the number plus one (7).