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?

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

What is more useful when it is broken?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

Jessica is telling her friends this story and asks them to guess if it’s the truth or a lie: “There was a man sitting in a house at night that had no lights on at all. There was no lamp, no candle, and no other source of light. Yet, he sat in the house and read his book happily.” Her friends say she’s lying, but Jessica corrects them and says she’s telling the truth. Jessica’s story is true—but how?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

Which is the correct shadow of the bird?

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