Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

Replace the question mark with the correct number in the below-given picture?

There are seven sisters in a house in a village where there is no electricity or any gadget.

Sister-1: Reading Novel
Sister-2: Cooking
Sister-3: Playing Chess
Sister-4: Playing Sudoku
Sister-5: Washing clothes
Sister-6: Gardening

what is Sister-7 doing ?

What is the next number in this series?

4,12,84,3612....

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

There is something which you can be arrested for attempting but not for successfully completing.

Can you find the least possible number such that

If the number is divided by 3, it gives the remainder of 1;
If the number is divided by 4, it gives the remainder of 2;
If the number is divided by 5, it gives the remainder of 3;
If the number is divided by 6, it gives the remainder of 4.

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?