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Difficulty: MediumNumber and Alphabet Series
Which of the following terms logically completes the given alphanumeric series?
D8W,F15U,I24R,M35O,?D8W, F15U, I24R, M35O, ?
  1. R48IR48IAnswer
  2. B
    R48JR48J
  3. C
    S48IS48I
  4. D
    R47IR47I

Answer

The term that logically completes the series is R48IR48I.
The first letter moves forward with increasing shifts of +2, +3, +4, and +5 (M + 5 = R). The middle number increases by odd consecutive differences +7, +9, +11, and +13 (35+13=4835 + 13 = 48). The last letter is the complementary reverse alphabet pair summing to 27 (27−18=927 - 18 = 9, which is I). Combining these yields R48IR48I.

Step-by-Step Solution

1
Analyze the pattern of the first letter in each term
D (4) →+2\xrightarrow{+2} F (6) →+3\xrightarrow{+3} I (9) →+4\xrightarrow{+4} M (13). The next shift is +5+5, giving 13+5=1813 + 5 = 18, which corresponds to R.
The positional step increases by 1 at each term.
2
Analyze the pattern of the middle numerical value
The numbers are 8,15,24,358, 15, 24, 35. The differences between consecutive terms are 15−8=715-8=7, 24−15=924-15=9, 35−24=1135-24=11. The next difference is +13+13, making 35+13=4835 + 13 = 48 (or 72−1=487^2 - 1 = 48).
The consecutive difference increases by 2 each time.
3
Analyze the pattern of the second letter in each term
Each second letter is the reverse alphabetical pair of the first letter (sum of positions = 27): D(4)+W(23)=27, F(6)+U(21)=27, I(9)+R(18)=27, M(13)+O(14)=27. For R (18th letter), the complementary position is 27−18=927 - 18 = 9, which corresponds to I.
The second letter maintains a constant complementary sum of 27 with the first letter.

Key Concept

Alphanumeric Series Completion via Multi-Pattern Analysis
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Topics

Number and Alphabet Series

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