Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

What time is it when an elephant sits on a fence?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

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?

Identify Me

Hint1: I am a god
Hint 2: I am a planet
Hint 3: measurer of heat

What does it mean?

When we see 2 but call 10?

You are playing as white and given four rooks to checkmate the black king in four moves with the following rules 1. You can place one rook every move and ensure the black king should be in check position.2. After four moves the black king should be in the checkmate position.

In a secret society, a buried chamber can be accessed only via a secret password. The password is seven characters long and comprises of just letters and numbers.

You find a code that can help you in cracking the password. The code says "You force heaven to be empty".

Can you deduce the password from that?

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?