Letter Series & Alphabet Test

Turn every letter into its position before you look for a pattern. A letter series is a number series in disguise, and the alphabet test is plain counting.

Keep three aids on the rough sheet: the positions A=1 … Z=26 (EJOTY: E=5, J=10, O=15, T=20, Y=25), the reverse rule (a letter's place from the right end is 27 minus its place from the left), and the opposite pairs A–Z, B–Y, C–X, whose positions add to 27.

The common patterns:

1. Fixed step. B, E, H, K, … moves +3 each time. Check the step on two pairs before trusting it.
2. Growing step. A, B, D, G, K, … has gaps 1, 2, 3, 4 that grow; write the gaps under the terms.
3. Two series woven together. A, Z, C, X, E, V, … — read the odd-numbered and even-numbered terms separately.
4. Letter groups. In ACE, BDF, CEG, … the first letter of each group and the step inside a group are two separate rules.
5. Alphabet test. "The 7th letter to the right of the 12th from the right end": convert the end first (27 − 12 = 15, which is O), then move (15 + 7 = 22, which is V).

The single most common mistake is counting an end letter as well — the letters between H and S number 19 − 8 − 1 = 10, not 11. The second is mixing up directions: to the right means towards Z in the normal alphabet, but towards A when the alphabet is written backwards.

How to check: put your answer back into the series and confirm that the rule produces it from the last term.

Convert letters to numbers first · EJOTY: E=5, J=10, O=15, T=20, Y=25 · place from the right = 27 − place from the left · opposite letters add to 27 · letters between two letters = difference − 1 · write the gaps; if they jump about, try the odd and even terms separately

Find the next term: B, C, E, H, L, ? → Positions 2, 3, 5, 8, 12; the gaps are +1, +2, +3, +4, so the next gap is +5 and 12 + 5 = 17, which is Q. Sanity check: Q − L = 17 − 12 = 5, exactly one more than the last gap of 4, so the growing-gap rule holds all the way through.