2 ladies and 2 girls need to cross a river in a boat big enough for 1 LADY or 2 girls. How do they do it?

What is next number in the pattern below:

131 517 192 123 ?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Find the last number in the series below:

voN luJ yaM raM ---

What is the word or phrase below?
R | E | A | D

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.

A red house is made out of red bricks. A yellow house is made out of yellow bricks. And, a blue house is made out of blue bricks. So, what is a greenhouse made of?

'S' refers to the number of seconds in a day and 'H' refers to the number of hours in ten years. Which quantity out of these two is greater?

A mules travels the same distance daily.
I noticed that two of his legs travels 10km and the remaining two travels 12km.
Obviously two mules legs cannot be a 2km ahead of the other 2.

The mules is perfectly normal. So how come this be true ?

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?