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

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

It can be easily calculated that the digits 0 to 9 can be arranged into 3628800 distinct ten-digit numbers.

But do you know how many of these numbers are prime?

What you cannot hold but it is yours?

I am white when I am dirty, and black when I am clean. What am I?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

A person was found dead on a big green land with no trees or buildings around. When the police arrived, they found a piece of rock lying next to him and the man was wearing clothes comprising of red, blue and yellow colours.

Can you tell who the person is and what was the cause of death?

John had a bag containing colourful marbles. The colours are red, green and blue. The total number of marbles he had in his bag was 60. There are 4 times as many red marbles as green marbles. 6 more blue marbles than green marbles. How many marbles of each colour did John have?

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?