Complete the table series riddle by finding the number that can replace "??".

What runs around the whole yard without moving?

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

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

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?

What does man love more than life, and hate more than death or mortal strife; that which satisfied men want; the poor have, and the rich require; the miser spends, the spendthrift saves, and all men carry to their graves?

Chocolate costs 6 rupees and a Toy costs 5 rupees. If you have 32 rupees in total, how many chocolates and how many Toys can be purchased with that amount?

A mathematics teacher took exams for his students. Out of the total students, 25% passed both the tests included in the exam. However, only 42% were able to clear the first test.

Can you find out the percentage of those students who passed the first test and also passed the second test?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?