If each letter is coded as its position in reverse (Z=1, Y=2,...A=26), what is ROAD?

Correct — D.
Rule: reverse value = 27 − alphabet position, since Z = 27 − 26 = 1 and A = 27 − 1 = 26.

R(18) → 27 − 18 = 9
O(15) → 27 − 15 = 12
A(1) → 27 − 1 = 26
D(4) → 27 − 4 = 23

ROAD = 9, 12, 26, 23 → option (d).

Why the others are wrong

• (a)
  10, 12, 25, 23 — 10 is the reverse value of Q, not R: 27 − 18 = 9. The option also codes A as 25, which is B's value.
• (b)
  9, 12, 25, 23 — 25 for A is B's reverse value. R, O and D are right, but A is the 26th letter counting back from Z, so it codes as 26.
• (c)
  9, 13, 25, 23 — 13 for O is N's reverse value, 27 − 14. O is the 15th letter, so it codes as 27 − 15 = 12, and A should be 26, not 25.

Reverse coding numbers the alphabet from the far end: Z = 1, Y = 2 … A = 26. A letter's forward and reverse numbers always add to 27, because Z is 26 one way and 1 the other.

So there is no need to count back from Z. Take the forward position you already know and subtract it from 27.

Key facts

• Forward position + reverse position = 27 for every letter.
• R is 18th forwards and 9th in reverse.
• M and N sit in the middle: M is 13 forwards and 14 in reverse.
• E = 5, J = 10, O = 15, T = 20, Y = 25 are quick anchors for forward positions.

Common traps

• Coding A as 25, as options (a), (b) and (c) all do. Counting back from Z, A is the 26th letter, so it codes as 26.
• Counting back from Z by hand and landing one letter off

No directly related past PYQ was found.