Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

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?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

Count the number of balls in picture below:

I travel all around the world but always stay in the corner. What am I?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

There’s a girl who has a large family. She has an equal amount of brothers and sisters, but each brother only has half as many brothers and sisters. What’s the correct amount of brothers and sisters?

You are mixing a mixture of cement and Sand with five gallons of water. You have a garden hose giving you all the water you need. The problem is that you only have a four-gallon bucket and a seven-gallon bucket and neither has graduation marks. Find a method to measure five gallons.

Why do you find that most of the buildings are deprived of the 13th floor?