# 666 (number)

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**666** is a natural number after 665 and before 667. It is a number with many properties.
One of these properties is that it is the sum of the first 36 natural numbers. That makes 666 a triangular number.
666 is the sum of the first 144 decimals (digits after the decimal point) of pi.^{[1]} The number is also used in the *666 dating rule* or *rule of sixes* which judges the attractiveness of men.

The Bible says in the Book of Revelation that the number 666 is associated with the Antichrist, the counter-messiah of the devil. People will be forced to accept this number as a mark on the penalty of death if they refuse. However, people who do accept this mark will be rejected by God.

## References

- ↑ Alfred S. Posamentier and Ingmar Lehmann 2009.
*Mathematical Amazements and Surprises: Fascinating Figures and Noteworthy Numbers*. Template:Catalog lookup link**Script error: No such module "check isxn".**.