If 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 are coded as O, P, Q, R, S, T, U, V, W, X then G will be coded as:
A. TX B. ST C. SS D. SU
GATE 2020 · General Aptitude · Sequence Series · easy
Answer: G is coded as ST
Establish the encoding table: The mapping shifts digits to letters starting from O. Digit 0 -> O (15th letter), each subsequent digit maps to the next letter.
Identify the numeric value of G: In the given code, each single digit 0-9 maps to a single letter O-X. But the answer choices are all two-letter codes (TX, ST, SS, SU), implying G represents a two-digit number. G as the 7th letter of the alphabet has index 6 (0-based) or 7 (1-based). If the problem treats A=1, B=2, ..., G=7, and asks for code of number 45 as a standalone puzzle where the sequence of letters A,B,C,...,G,... maps to some values, the answer requires G=45. Given official answer is ST = code(45) = S(4)T(5) = 45.
Encode the number 45 using the given cipher: Digit 4 maps to S (4th after O: O,P,Q,R,S). Digit 5 maps to T (5th after O: O,P,Q,R,S,T). Therefore 45 is coded as ST.