Prove that twice of ten is the same as twice of eleven.

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

Can you find the hidden animal in the picture below?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

In four steps you need to move the word 'cold' From 'warm' by replacing one alphabet at a time such that every word formed at each step is acceptable in English Dictionary.

Decode below rebus
D
N
A
T
S , D

Why 1729 is a magic number? Answer Logically.

It belongs to you, but other people use it more than you do. What is it?