How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

It can't be seen, can't be felt, can't be heard, and can't be smelt.
It lies behind stars and under hills, And empty holes it fills.
It comes first and follows after, Ends life, and kills laughter.
What is it?

There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

Can you write down eight eights so that they add up to one thousand?

A large container is kept in open under the rain. Every passing hour, the water collected inside the container becomes double what it was.

In ten hours, the container is filled completely. Can you calculate how long would it have taken to be filled in half?

The sum of a mother, her baby and her dog's weight is 170 Kg. How much does the baby weigh if the mother weighs 100 kg more than the combined weight of the baby and the dog, and the dog weighs 60 per cent less than the baby?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

What has no start, end, or centre?

Move three sticks of the spiral below to form a square.