What is in seasons, seconds, centuries and minutes but not in decades, years or days?

What 5-letter word typed in all capital letters can be read the same upside down?

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

What came first, the chicken or the egg?

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

You measure my life in hours
I serve you by expiring
I vanish faster when I am thin
and slower when I am thick
The wind is my energy
What am I?

John and Jacob are twin brothers. One of them is a liar whereas the other one is a truth-teller.

I called their home number and one of them picked up.
I asked. 'Does John lie?' The person replied with a yes.

Whom did I talk with, John or Jacob?

What goes up but never comes down?

Find the next number in the series below

21 32 54 87 131 ?