Free the World’s Shortest IQ Test: What Is the 3-Question IQ Test?

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Last updated: 08/22/2025

Recently, one particular “IQ test” has gone viral across social media: the 3-question IQ test, also known as the Cognitive Reflection Test. Despite its simplicity, it has sparked deep conversations about intelligence, problem-solving, and how we think.

In this article, we’ll unpack what the 3-question IQ test really is, where it came from, what it does and doesn’t measure, and whether it has a place in the classroom or at home as a learning tool.

What Is the 3-Question IQ Test?

Definition and Origin

The so-called 3-question IQ test is not actually a full IQ test. It’s a condensed version of the Cognitive Reflection Test (CRT), a short assessment developed by behavioral economist Shane Frederick in 2005.

Frederick designed the CRT to measure a person’s tendency to override an initial, incorrect “gut” response and engage in further reflection to find the correct answer. It’s not about how smart you are in the traditional IQ sense—it’s about how you think.

Source: Shane Frederick. “Cognitive Reflection and Decision Making.” Journal of Economic Perspectives

What Are the 3 Questions?

3 question iq test questions

Here are the original three CRT questions:

1.A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the ball cost?

Common wrong answer: 10¢
Correct answer: 5¢ (The bat is $1.05, and the ball is $0.05)

2.If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets?

Common wrong answer: 100 minutes
Correct answer: 5 minutes (Each machine makes 1 widget in 5 minutes)

3.In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take to cover half the lake?

Common wrong answer: 24 days
Correct answer: 47 days (The lake is half-covered the day before it’s fully covered)

Each question is designed to trigger an intuitive but incorrect answer, prompting deeper thought to arrive at the correct one.

What Does the Test Actually Measure?

Fast vs. Reflective Thinking

To understand this test’s purpose, we can look to Nobel Prize-winning psychologist Daniel Kahneman, who described two systems of thought in his book Thinking, Fast and Slow:

System 1: Fast, automatic, emotional, and intuitive.
System 2: Slow, effortful, logical, and reflective.

The CRT tests how likely someone is to engage System 2 thinking. It challenges us to pause, double-check our instincts, and apply logic—even when the “obvious” answer feels right.

Is 3-Question IQ Test a Real IQ Test?

In short: No. While it’s often called an “IQ test” online, the CRT does not assess the full spectrum of intelligence like standardized IQ tests such as the Wechsler Intelligence Scale for Children (WISC) or Stanford-Binet.

Instead, it measures cognitive reflection—a specific thinking skill that’s valuable, but just one part of broader intelligence.

IQ tests cover areas like:
Verbal reasoning
Working memory
Processing speed
Spatial reasoning
Mathematical problem-solving

Why Is the 3-Question IQ Test So Popular?

iq test

Social Media and Viral Challenges

On platforms like TikTok, YouTube, and Instagram, influencers challenge followers to solve the three questions “on the spot,” making it a fun, fast-paced brain game. Its appeal lies in simplicity—and the surprise when smart people get it wrong.

This “aha” moment drives engagement, shares, and comments. The questions are deceptively easy, which makes failing them feel both frustrating and funny, a perfect recipe for virality.

Appeal of Simplicity and Speed

Let’s face it: no one’s pulling out a full IQ test on a lunch break. The 3-question test offers:

Instant results
Social comparison (“I got 2/3—how did you do?”)
A sense of mental challenge without the time commitment

It feeds into the modern craving for quick knowledge checks and bite-sized self-assessments.

Should Teachers or Parents Use It?

As a Thinking Exercise

Absolutely! While it’s not a diagnostic tool, the CRT can be used in educational settings as:

A warm-up activity for math or logic classes.
A critical thinking discussion starter.
An example of how our minds sometimes trick us.

It encourages metacognition, thinking about how we think, which is vital in developing reasoning and problem-solving skills.

Tip for Teachers: Use it to spark a conversation about intuitive vs. analytical thinking. Ask students to explain their reasoning process, not just give the answer.

Platforms like Wukong Math are already incorporating these kinds of exercises into structured, age-appropriate problem-solving sessions for K–12 students. With a curriculum designed to build both speed and accuracy in math thinking, Wukong Math helps children strengthen not just basic skills, but also the deeper logic and reflection abilities that tests like this reveal.

What Not to Do

Here’s what not to do with the 3-question IQ test:

Use it to label students as smart or not smart.
Rely on it for assessing academic potential.
Present it as a true IQ score or psychological evaluation.

Remember: It’s just one small, fun tool—not a full reflection of intelligence or learning ability.

Final Thoughts

The 3-question IQ test is a fascinating, accessible window into how we think—but it’s often misunderstood. Originally designed as a Cognitive Reflection Test, it was never meant to measure intelligence in the traditional sense. Instead, it tests our ability to pause, reflect, and resist jumping to conclusions. As educators, parents, or curious learners, we can use it to promote reflective thinking, but we should also clarify its purpose and limitations. Intelligence is multifaceted and complex, no three questions can sum it all up.

So next time you see this test online, go ahead and give it a try, but don’t let a quick score define your thinking power.

Looking for structured, fun online math classes for kids? WuKong Math offers age-appropriate lessons from grades 1 to 12.

Sources:

Shane Frederick. “Cognitive Reflection and Decision Making.” Journal of Economic Perspectives
Daniel Kahneman. Thinking, Fast and Slow. Farrar, Straus and Giroux, 2011.
American Psychological Association. “Intelligence and Achievement Testing: Is the Half-Full Glass Getting Fuller?”

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Nathan | WuKong Math Teacher

Graduated from the University of New South Wales. He has over 8 years of experience teaching elementary and high school mathematics and science. As a rigorous and steady mathematics teacher, Nathan has always been well received by students 1-12 grades.