Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

A frog is at the bottom of a 30-meter well. Each day he summons enough energy for one 3-meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

An artist while painting a scenic beauty, decides to paint three layers of blue colour on the sky.

Which layer will go on the first?

Find three numbers such that When we multiply three numbers, we will get the prime numbers. The difference between the second and the first number is equal to the third and second.

Why do we preferably have round manhole covers and not square ones?