All roses are flowers. Some flowers fade quickly. Which statement must be true?

Nothing about roses fading follows

The Ultimate IQ and Logic Quiz: 10 Brain Teasers That Get Tricky

The ultimate IQ and logic quiz brings together ten brain teasers that start easy and get tricky, with number patterns, letter codes, word analogies, age puzzles, clock angles, family riddles and classic logic traps, in the spirit of Martin Gardner, the famous puzzle writer of Scientific American. It is a fun practice set, not an official test. Beat the 150-second timer.

Start The Ultimate IQ and Logic Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Numbers
What number comes next: 3, 6, 12, 24, ...?
Letters
If DOG is written as EPH in a code, how is CAT written?
Analogy
Book is to reading as fork is to what?
Ages
Sara is twice as old as her brother. In 4 years she will be 20. How old is her brother now?
Clocks
What is the smaller angle between the hands of a clock at exactly 3 o'clock?
Family
A man looks at a photo and says: Brothers and sisters I have none, but this man's father is my father's son. Who is in the photo?
Logic
All roses are flowers. Some flowers fade quickly. Which statement must be true?
Odd one out
Which number does not belong: 2, 3, 5, 9, 11?
Sequences
What letter comes next: B, E, H, K, ...?
Speed
If 3 cats catch 3 mice in 3 minutes, how many cats are needed to catch 100 mice in 100 minutes?

Explanations: answer key for all 10 questions

Q1: What number comes next: 3, 6, 12, 24, ...?
Answer: 48
Each number in the sequence is double the one before it. Doubling 24 gives 48, the next number.
Q2: If DOG is written as EPH in a code, how is CAT written?
Answer: DBU
Each letter moves one place forward in the alphabet: D to E, O to P and G to H. So C becomes D, A becomes B and T becomes U.
Q3: Book is to reading as fork is to what?
Answer: Eating
A book is a tool for reading, and a fork is a tool for eating. The link is between an object and its use.
Q4: Sara is twice as old as her brother. In 4 years she will be 20. How old is her brother now?
Answer: 8
Sara is 16 now, because 16 plus 4 equals 20. Half of 16 is 8.
Q5: What is the smaller angle between the hands of a clock at exactly 3 o'clock?
Answer: 90 degrees
The minute hand points at 12 and the hour hand at 3. Each hour mark is 30 degrees apart, so three marks make 90 degrees.
Q6: A man looks at a photo and says: Brothers and sisters I have none, but this man's father is my father's son. Who is in the photo?
Answer: His son
The speaker has no brothers, so my father's son must be the speaker himself. The man in the photo is the son of the speaker.
Q7: All roses are flowers. Some flowers fade quickly. Which statement must be true?
Answer: Nothing about roses fading follows
The flowers that fade quickly might not be roses at all. The premises do not tell us anything certain about roses fading.
Q8: Which number does not belong: 2, 3, 5, 9, 11?
Answer: 9
All the others are prime numbers. 9 can be divided by 3, so it is not prime.
Q9: What letter comes next: B, E, H, K, ...?
Answer: N
Each letter jumps forward by three places in the alphabet: B, E, H, K and then N.
Q10: If 3 cats catch 3 mice in 3 minutes, how many cats are needed to catch 100 mice in 100 minutes?
Answer: 3
Each cat catches one mouse every three minutes. In 100 minutes, 3 cats working at that rate can catch 100 mice.

The Ultimate IQ and Logic Quiz – Brain Teasers That Get Tricky

Logic puzzles and brain teasers are a fun way to exercise your mind. They test skills such as spotting patterns, following rules, reading carefully and thinking step by step. Many of the question types in this quiz appear in puzzle books, school challenges and job aptitude tests.

The quiz begins with friendly patterns, such as numbers that double and letters that jump forward. It then moves to analogies, coded words and age problems, where writing down what you know helps a lot. Clock and family puzzles add a twist, and classic logic traps check whether you add assumptions the facts do not support.

The final question is a famous puzzle about cats and mice. It looks like it needs complex math, but a calm look at the rate of each cat solves it quickly. The American writer Martin Gardner, who wrote a puzzle column in Scientific American for 25 years, loved questions like this because they reward clear thinking over hard work.

Remember that this quiz is for practice and fun. A score here is not a measure of intelligence, but practicing puzzles regularly can make your reasoning faster and more confident.

If a question stumps you, read the explanation slowly and then try a similar puzzle on your own. Many people find that the same patterns appear again and again, so each puzzle you solve makes the next one easier.

What This Quiz Teaches

This quiz is perfect for puzzle fans, students and families.

Number and letter sequences
Codes and analogies
Age and clock puzzles
Family riddles
Logic traps
Rate problems

Quick Facts About Brain Teasers

Martin Gardner wrote his Mathematical Games column from 1956 to 1981.
Puzzles appear in some of the oldest surviving math texts.
Sudoku became a worldwide craze in 2005.
Writing down clues is the best way to solve logic puzzles.
Many puzzles have more than one solving method.
Short daily puzzles are a popular way to keep the mind active.