If eleven plus two equals one, what does nine plus five equal?

The more of this there is, the less you see. What is it?

I go up and I go down.
I go up towards the beautiful sky and down toward the green ground.
I am present tense.
I am past tense too
Children love me.

Who Am I?

I have an eye but still cannot see.

Who am I?

My first is in chocolate but not in ham. My second is in cake and also in jam. My third at tea time is easily found. Altogether, this is a friend who is often around. What is it?

What has to be broken before you can use it?

How can you take 2 from 5 and leave 4?

How many sides does a circle have?

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 have a head like a cat and feet like a cat, but I am not a cat. What am I?