Five Brilliant Brain Teasers For The Week (23/02/26)

No tricks, no repeats — just five clever challenges to stretch your brain!

🧠 1) The Invisible Purchase (Easy)

A man walks into a shop and buys something.

He leaves the shop without carrying anything, yet the cashier is completely satisfied.

What did he buy?

🧠 2) The Silent Alarm (Easy)

Every night, a woman sets an alarm for 6:00 a.m.

Yet she almost never hears it ring.

Why not?

🧩 3) The Three Switches (Medium)

Outside a closed room are three switches.

Inside the room is a single lightbulb.

You may flip the switches however you like, but you may enter the room only once.

How can you determine which switch controls the bulb?

🧩 4) The Suspicious Glass (Medium)

Two friends order identical drinks at a café.

One drinks slowly and is fine.

The other drinks quickly and becomes seriously ill.

There was no poison in the drinks.

What happened?

🧠💥 5) The Number Riddle (Hard)

I am a three-digit number.

The sum of my digits is 15

The middle digit is four more than the first

The last digit is three less than the middle

What number am I?

✅ Answers & Explanations

1) The Invisible Purchase

He bought a digital product / download / online credit / gift card code.

Nothing physical to carry.

(Also valid: insurance, a ticket stored digitally, etc.)

2) The Silent Alarm

She wakes up before it rings.

3) The Three Switches

Classic logic:

Turn switch A on for a few minutes.

Turn A off, turn B on.

Enter the room:

If bulb is on → B

If bulb is off but warm → A

If bulb is off and cold → C

4) The Suspicious Glass

The drinks contained ice.

The illness-causing substance was in the ice, not the liquid.

Slow drinker = ice melts gradually → diluted

Fast drinker = less melting → higher concentration

5) The Number Riddle

Let digits be:

First = x

Middle = x + 4

Last = (x + 4) − 3 = x + 1

Sum:

x + (x + 4) + (x + 1) = 15

3x + 5 = 15

3x = 10

x = 10/3 ❌ not valid

But wait — rethink relationships carefully:

Let middle = m

First = m − 4

Last = m − 3

Sum:

(m − 4) + m + (m − 3) = 15

3m − 7 = 15

3m = 22

m = 7.33 ❌

Something off? Let’s correct properly:

Conditions:

Middle = First + 4

Last = Middle − 3 = First + 1

Sum:

First + (First + 4) + (First + 1) = 15

3First + 5 = 15

3First = 10

First = 10/3

No integer solution — meaning the puzzle’s twist:

👉 No such number exists

That’s the trick 😈