An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

A Car is crossing a bridge 2 miles long. The bridge can only hold 10000 lbs, which is the exact weight of the car. The Car makes it half way across the bridge and stops. A bird lands on the car. Does the bridge collapse? Explain.

What question can you never answer yes to?

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

No matter how little or how much you use me, you change me every month. What am I?

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?