Concepts · Letter series and coding

Letter positions

You do not have to count from A every time.

Riya is on question 31 of a mock test:

If CAT is coded as 24, how is DOG coded?

She starts on her fingers. C is 3, A is 1, fine. Then T: A, B, C, D, E, F, G, H… somewhere around P she loses her place and starts again from A.

The clock on the wall

She looks up at the clock to see how much time she has wasted. The minute hand is two marks past the 3. Seventeen past.

Then she looks again. She did not count seventeen marks from the 12. She read the 3 as fifteen and added two.

A clock face prints a number every five minutes, so there is no need to count from the top. The alphabet has no numbers printed on it. So, in the margin of the question paper, Riya prints five of her own.

The rule

Every letter has a position, from A = 1 to Z = 26. Learn five anchors, E 5, J 10, O 15, T 20, Y 25, and say them as one word: EJOTY.

Every letter from C to Z is at most two steps from an anchor. A and B you know already.

Riya’s question, again

1. CAT: C is two before E, so 3. A is 1. T is an anchor, 20. 3 + 1 + 20 = 24, so the code is the sum of the positions.
2. DOG: D is one before E, so 4. O is an anchor, 15. G is two after E, so 7.
3. 4 + 15 + 7 = 26.

Two steps per letter, at most. No fingers, and the minute she lost came back on the next three questions.

The other way round

Which letter is 17? The nearest anchor is O, 15. Two after O: P, Q. The answer is Q.

Why it helps in the paper

Letter series, coding and word questions all become number questions the moment you write the position under each letter. Once the positions are there, the rest is arithmetic. Counting from A every time is the slow part, and the anchors remove it.

Counting from Z instead? That is Opposite letters. Going past Z? Wrapping past Z.

Try three

Next mock

A week later Riya meets the same kind of code: PEN = ? P is one after O: 16. E is 5. N is one before O: 14. She writes 35, and her fingers never leave the desk.