The cognitive reflection test is the world’s shortest IQ test


Can you pass the world’s shortest IQ test? Three questions can reveal if you have above average intelligence (but it’s a lot harder than it looks)

  • The cognitive reflection test was published in Journal of Economic Perspectives
  • Has resurfaced due to Donald Trump and Rex Tillerson’s argument over IQ tests
  • The assessment contains only three questions and looks quick and easy to complete
  • But the key is to understand why the questions are so much harder than they appear.

Getting into Mensa involves taking a test with dozens of questions, but apparently there’s an easier way to check if you have a higher IQ.

The Cognitive Reflection Test is the world’s shortest IQ test and contains just three questions, which at first glance seem relatively straightforward.

Published in 2005 in the Journal of Economic Perspectives, the test resurfaced online following US Secretary of State Rex Tillerson’s challenge to Donald Trump to “compare IQ tests” after reports he called the test. president of “moron”.

The quick test would be an ideal option for two such busy men to sort out their dispute as it only has three questions.

However, the test is actually much trickier than it looks and the proof of a high intellect is to take it and craft the answers accordingly.

Scroll down to take the test and find out if you have above average intelligence.

The cognitive reflection test is the world’s shortest IQ assessment and can predict if you have above average intelligence (stock image)


1. A bat and ball cost £ 1.10 in total. The bat costs £ 1.00 more than the ball. How much does the ball cost?

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

3. In a lake, there is a square of water lilies. 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 for the patch to cover half of the lake?


1.10 cents

2.100 minutes

3. 24 days


question 1

If the ball costs X and the bat costs £ 1 more, then the cost is X + £ 1

So Bat + ball = X + (X + 1) = 1.10

This means 2X + 1 = 1.1 and 2X = 0.1 and X = 0.05

Correct answer: five pence

question 2

If five machines can create five widgets in five minutes, one machine will make one widget in five minutes.

So if 100 widgets all make widgets, they can make 100 in five minutes.

Correct answer: 5 minutes

question 3

If the lily pad completely covers the pond by day 48 and has doubled in size, that means you only have to go back one day to when it covered half the pond. So, on day 47, the lake is half full.

Correct answer: 47 days


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