What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

How many triangles can you find in this given picture?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

I have no life, but I can die. What am I?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

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

What does this rebus riddle means ?

How can you tell a raw egg from a hard-boiled egg?

In a stable, there are men and horses. In all, there are 22 heads and 72 feet. How many men and how many horses are in the stable

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.

How do you measure 45 minutes?