Intresting Maths Riddles 

Three friends split a bill of $30.
They each pay $10.
Later, the waiter realizes the bill was only $25, so he gives back $5.
They each take $1, and give $2 to the waiter as a tip.
So they each paid $9, totaling $27. Add the $2 tip → $29.
Where is the missing dollar?

ANSWER>  There is no missing dollar. The error comes from adding the $2 tip to the $27, when in fact the tip is part of the $27.

It's just a logical trick.

2. The Disappearing Painting, A thief stole a painting from a museum with 24/7 security. No alarms went off. No one broke any locks. But the next morning, the painting was gone. Security footage shows no one entered or left. How was it stolen?

Answer: The thief hid inside the museum overnight.

3. The Hat Trick You see five people in a line. Each wears a red or blue hat. They can only see the hats in front of them. Each is asked (from back to front): “What color is your hat?” The last person (who sees all 4 in front) always guesses right. How?

ANSWER> They use a pre-arranged parity strategy (e.g., say "red" if number of red hats is even).
It’s logic, not luck.

4. Add me to myself and multiply by 4. Divide me by 8 and you get me back. What number am I?

ANSWER> —Any number

5. If 3 cats catch 3 mice in 3 minutes, how long for 100 cats to catch 100 mice?

ANSWER> — 3 minutes

6. A stick is broken into 3 random pieces. What’s the chance they form a

triangle?

ANSWER> — ¼

7. How many times do the hour and minute hands overlap in 12 hours?

ANSWER> — 11 times

8. Multiply me by any other integer and the result is never prime.

ANSWER> 0 or 1 (strictly: 0; 1×prime = prime, so answer: 0)

9. A pirate finds 10 gold coins and splits them evenly among 5 crew members, keeping none. How many coins per crew member?

Answer: 2. (10 ÷ 5 = 2.)

10. “If you add my age to yours, the total is 90,” Grandpa says. If you are        25, how old is Grandpa?

Answer: 65. (90 − 25 = 65.)