Everything around us is made out of numbers. Paying for goods in the shops, calculating the distance on the satellite navigator, using computers, dialing a phone number, setting a timer, choosing the amount of minutes for heating your food in a microwave, running the mile, and so on, – everything is based on numbers. Even human biology can be described with numbers. But there always were numbers which had a special meaning for people. Thus, one of such numbers is three. It is a number which is connected to a big amount of scientific, cultural, and other facts.

### Number Three and Mathematics

First of all, number three has a big significance for mathematics. It is the first odd and the second smallest prime number. Number three is also divisible by three in case the sum of the digits is divisible by three. This number is the second triangular and the only prime triangular number. It is the fourth Fibonacci and open meandric number. There exist only three distinct 4×4 panmagic squares.  It was proved by Gauss that every integer is the sum of most three triangular numbers. Any number that does not have the form of 4n(8m+7) is the sum of three squares.

### Number Three and Science

Number three is also important for science. For example, the weight of an adult human brain is 3 pounds. There are three dimensions: length, height, and width. There are three states of time: past, present, and future. Earth is the third planet from the Sun. There are three prime colors: red, green, and blue. There are three biological kingdoms: animals, plants, and minerals. There is a reflection of `trilogy` in the human body and biology. For instance, there are three semicircular canals in a human ear and three ossicles in a human middle ear. Human elbow consists of three bones. Genetic information in DNA and RNA is encoded with the use of a triplet codon system.

Chemistry is not an exception; it also has some facts connected to the number three. It is the atomic number of a chemical element called lithium. There are three constituents that form atoms: protons, electrons, and neutrons.

### Number Three, Religion, and Mystery

Three has a strong connection with Christianity and other religions. Moreover, it is full of magical and spiritual meaning for Esotericism. It is a well known fact that The Bible has a big amount of references to the number three. The significance of the third day in the Bible, the Holy Trinity in Christianity, the Trimurti and Tridevi in Hinduism, the three jewels in Buddhism, the three pure ones in Taoism, the triple Goddess in Wicca, and many more symbols show how important they were for different religions. Three people (one of who was Jesus) were crucified at the Crucifixion. The Holy Family consists of three members: Mary, Jesus, and Joseph. When Jesus was born, the wise men gave him three gifts. All the world major religions can be divided into three groups: Abrahamic, Indian, and East Asian religions. Meanwhile, Abrahamic religions are also divided into three: Christianity, Islam, and Judaism.

Three has always had a mysterious meaning as a very lucky number in some countries and a very unlucky number in the others. It is also popular in stories and fairy tales as a magical number.

Therefore, there are many interesting facts about the number three in every sphere of everyday life, science, and culture. It was believed to have a special meaning and a unique power for many years. That is why people tried to connect its meaning to every activity and event in their lives.