Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

I have an eye but still cannot see.

Who am I?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

How many times can you subtract the number two from the number fifty?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

I hide my treasure in the ground, my tail is big and fluffy. If you spot me in a tree, please don’t call me scruffy. What am I?

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?