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

Today is John's birthday.
A year ago, John had five candles and he lit all the candles except the one at the last.
Now he is going to light all the candles.

How old is John Today?

(He is not five today.....)

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

Solve The below Equation:

ALFA + BETA + GAMA = DELTA

Can you discover the missing number in this series?

37, 10, 82
29, 11, 47
96, 15, 87
42, ?, 15

Can you find out the remainder when 3^300 is divided by 5?

In order to complete the racing competition, the Mexico racetrack has to submit its top and the most famous three horses to win the competition. Due to an electrical storm, all the records are cleared and no one knows which horse holds the record. They all look identical and it becomes even more difficult to differentiate the horses. There are 25 horses in the Mexico racetrack. But there can be only five horses at a time on the track. What will the least number of races that can be conducted to find out the three fastest horses?

John can fit six large chocolate boxes or nine small chocolate boxes into a carton. How many cartons will he require to put sixty-six chocolate boxes into?

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

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?