Brain teaser: Test your mind with this blind-draw marble puzzle that is trickier than it looks

Here’s a tricky brain teaser that challenges users to find the solution to a marble puzzle.

Brain teasers are short, clever puzzles designed to make the mind think in fresh ways. They often look simple, but they push us to use logic, patience, and careful observation.

X users found the brain teaser tricky and surprising. (@mariashriver/X)

Solving a brain teaser, even a tiny one, gives a small mental boost and makes the brain feel more active.

Here's such a brain teaser posted on X (formerly Twitter) by Maria Shriver, which challenges you to find the minimum blind draws needed to guarantee all three colours in a marble puzzle.

“Your brain likely needs a little brain teaser today,” the caption of the brain teaser reads.

What is the brain teaser all about?

The brain teaser asks you to imagine a box filled with 13 blue marbles, 13 red marbles, and 13 green marbles, all mixed together, where you cannot see inside.

The challenge is to work out the minimum number of marbles you would need to pull out, without looking, to be completely sure that you end up with at least one marble of each colour.

“A box holds 13 blue marbles, 13 red marbles, and 13 green marbles. If you're unable to see into the box, what is the minimum number of marbles you need to take out to ensure you have one of every color?” the brain teaser reads.

Check out the brain teaser here:

Here's how people reacted to the brain teaser:

X users found the brain teaser tricky and surprising. Many first guessed a very small number of marbles, only to realise it required a bit more careful thinking.

One of the users commented, “This depends…will you be drawing blindly, not seeing/knowing what each draw is…or you will see/know what color you’ve drawn each time.”

A second user commented, “Trick question, it's unclear if one of each colour means outside the box or inside the box.”

“3 if you get lucky and get one of each colour,” another user commented.

The post was shared on November 28, 2025, and since then, it has gained 16,000 views and more than 50 comments.