What is the next number in this series?

4,12,84,3612....

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

How many times in a given day, minutes and hour clock comes in a straight line ?

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

Find the missing letter in the last circle logically in the given below picture.

Given below is simple addition with a defined pattern pattern:
7 + 7 = 2
8 + 8 = 4
8 + 5 = 1
6 + 9 = 3
10 + 11 = 9

Can you analyze the pattern and find out the answer for:

4 + 9 = ?

In a science lab, a petri dish hosts a healthy colony of yeast for an experiment. Now every minute, all the yeast cells divide into two. At noon, there was just a single cell of yeast and at 1:22, the Petri dish was half full. Can you calculate when the dish will be full of yeast?

It's a test that will check your IQ.

Suppose you have one 11 minute hourglass and one 13 minute hourglass.

Can you measure exactly fifteen minutes using them ?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?