Why is number 7?

Thai people, the favorite number would be 9 because the meaning in Thai is moving forward or prosper. However, I like number 7 and it is the world's most favorite number too because it might be the most unique number with one or more following 7 reasons.

1. 7 is the maximum one digit that is prime ( 2 3 5 7), and 7 is a unique number because there is no shortcut for the divisibility rule. You need to do it straightly. The others have a shortcut  

        2: all even numbers can be divided by 2,

        3: the sum of all the digits of that number can be divided by 3, 

        4: the last 2 digits can be divided by 4,

        5: the last digit of that number has to be 5 or 0,

        6: the number that must be divided by both 2 and 3,

        8: the last three digits of that number can be divided by 8,

        9: the sum of all digits of that number can be divided by 9.

 and 7: double the last digit, subtract to the rest numbers, the result must be divided by 7. There is no shortcut!

2. 7 is the lucky number of western because God made the world in six days and rested on the seventh day. After the rain, the sky will be clear so you can find 7 colors in the rainbow.

3. 7 is the maximum thing that humans can memorize best such as 7 days in the week.

4. 7 is the 7 habits of highly effective people, the popular self-improvement book.

5. 7 is the seven-eleven store that we see everywhere and use every day.

6. 7 is the number of Cristiano Ronaldo, my idol for work and life attitude.

7. 7 is the code number of Bond, James Bond, my identity.