Concept 3 of 6
Alphabet Series: The Next Letter
Today's big idea
Count the step between two letters, then walk that same step onward.
A, C, E, G skips one letter each time, a step of +2, so next is I.
How it works
👀 What's going on?
Letters can hide a rule just as numbers do. The alphabet works like a track, and each step moves you a fixed number of places along it.
💡 Here's the trick
Look at the step above. Moving from one letter to the next skips exactly one letter, which is a step of +2, so G becomes I. Count the step once, check it still holds for the next pair, then walk that same step on from the final letter.
🪄 How to do it
- 1.Say the alphabet and count the step between the first two letters, as the picture above counts +2.
- 2.Check that the same step works for the next pair too.
- 3.Walk that step on from the last letter given.
✍️ Try it
Find the next letter in B, E, H, K, ? Then find the next letter in Y, W, U, S, ?
B, E, H, K steps forward by 3 each time, so the next is N. Y, W, U, S steps backward by 2 each time, so the next is Q. A backward step is every bit as regular as a forward one.
⚠️ Watch out
You might be thinking you can count the step by eye. Write the alphabet out for the first few questions. Guessing that P to T is a step of 3 rather than 4 is the commonest way these go wrong.
🌟 Why this matters
Reading a rule off a sequence is the same skill whether the items are letters, numbers or shapes. It is also exactly what makes secret codes and ciphers work.
Exam tip: Write A to Z once along the top of your rough page, and every letter question after that gets quicker.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Find the next letter: C, G, K, O, ?”
- 1
Count the step
C → G skips three, so +4. Every step is +4.
- 2
Walk +2 from G
O → (skip P, Q, R) → S
- 3
Answer ✓
Next = S
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Each hop is +2 along the alphabet. Hop to the next letter.
ALPHABET SERIES · ROUND 1 OF 3
K, M, O, Q, ?
Quick check
✅ VERIFICATION
Find the next letter: D, H, L, P, ?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Alphanumeric Series
Two rules, two tracks. Solve each track, then combine.