How can a man go eight days without sleep?

There are 2 sand hourglasses.

The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

Take number 1000 and then add 20 to it.
Now add 1000 one more time.
Now add 30.
Now add 1000 one more time.
Now add 40.
Now add 1000 one more time.
Now add 10.

What is the total?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

I’m tall when I’m young, and I’m short when I’m old. What am I?

I am thinking of a five-digit number such that:
The first and last digits are the same, their submission is an even number and multiplication is an odd number and is equal to the fourth number. Subtract five from it and we obtain the second number. Then divide into exact halves and we get the 3rd number.

What number I am thinking of?

In the below-given picture of a pretty girl, there is something wrong. Can you find out what it is?

Find the hidden tiger in the given optical illusion ?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

How many bricks does it take to complete a building that is 15 feet wide, 30 feet deep, and 12 feet tall made of brick?