Concept 4 of 6
Alphanumeric Series: Letters & Numbers Together
Today's big idea
Split the letters from the numbers, solve each rule alone, then recombine.
A2, C4, E6, G? gives letters +2 and numbers +2, so the answer is G8.
How it works
👀 What's going on?
Some series mix letters and numbers together, like A1, B2, C3. Hunting for one rule that covers both is hopeless. There are two rules, running side by side.
💡 Here's the trick
Look at the two tracks above. The letters go A, C, E, G, stepping +2 each time. The numbers go 2, 4, 6, 8, also stepping +2. Solve each track on its own, then put the answers back together as G8. Two easy rules beat one impossible one.
🪄 How to do it
- 1.Read only the letters and find their step, as the top track in the picture above does.
- 2.Read only the numbers and find their rule.
- 3.Combine the next letter with the next number.
✍️ Try it
What comes next in B1, D3, F5, H? Work the letters out first, then go back for the numbers.
The letters run B, D, F, H, stepping +2, and the H is already given to you. The numbers run 1, 3, 5, also stepping +2, so the missing one is 7. Together that makes H7.
⚠️ Watch out
You might be thinking the letter and the number always move by the same amount. Very often they do not. In A1, C2, E3 the letters step +2 while the numbers step +1, so each track has to be checked on its own.
🌟 Why this matters
Seat numbers, house addresses and car registration plates all mix letters with numbers, and each part follows its own pattern. Splitting them is how anyone reads them quickly.
Exam tip: Cover the numbers with a finger and solve the letters, then swap. It beats staring at both at once.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“Find the next pair: M1, O2, Q3, S?”
- 1
Split the tracks
Letters: M, O, Q, S. Numbers: 1, 2, 3, ?.
- 2
Solve LETTERS only
M → O → Q → S : skip one letter each time (+2). Letter is set: S.
- 3
Solve NUMBERS only
1, 2, 3 : +1 each. Next: 4.
- 4
Combine ✓
Pair = S4
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Step the letter track and the number track to build the next pair.
ALPHANUMERIC · ROUND 1 OF 3
LETTER TRACK
B, D, F, ?
NUMBER TRACK
1, 2, 3, ?
Quick check
✅ VERIFICATION
What comes next: C3, F6, I9, L?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Growing Figure Patterns
Count each figure, then it's just a number series.