Find out the missing number in the picture attached:

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?

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?

I am lying and I always lie. Tell me whether I am lying or telling the truth.

Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

What is the longest word in the dictionary?

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.

We can be boring,Or interesting.
We can be long,Or short.
We can have pictures,Or just words.
Many love us,But many also hate us.
What are we?

He runs but never walks. Murmurs, but never talks. Has a bed, but never sleeps. And has a mouth, but never eats?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?