Find the Next Letter After A, C, F, J, O

What was yesterday's answer?

Quiz 5 was about finding who among three people is telling the truth. The answer is only B.

1. Suppose C is telling the truth. Then A and B are both liars. But for the liar A's statement "B is a liar" to be false, B would have to be truthful, which is a contradiction.
2. So C is a liar. Then B's statement "C is a liar" is true, so B is telling the truth.
3. A's statement "B is a liar" is false, so A is a liar.
4. Finally, C's statement "A and B are both liars" is false because B is truthful, which fits the conclusion that C is a liar.

What is today's puzzle?

• Difficulty: ★★☆☆☆
• Suggested time: 3 minutes
• Tip: it helps to turn letters into position numbers, with A as 1st, B as 2nd, and so on

Where should you start?

If you turn the letters into position numbers, it becomes a number sequence puzzle. After converting, write the differences between neighboring numbers. You can use the same method you tried in Quiz 1 and Quiz 4.

When can you check the answer?

The answer and explanation go up tomorrow (October 19) morning, at the very top of the Quiz 7 post. It will come with an alphabet number chart as well.

How do letter patterns differ from number puzzles?

A letter pattern only adds one step, turning letters into position numbers, and the way you find the rule is the same as for number sequences. Mensa Korea describes its online brain test as looking at pattern recognition (checked 2026-10-13). Mensa International's membership standard is a top 2% score on an approved intelligence test, and this puzzle is for practice.