## Perfect Numbers

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The perfect numbers are 6, 28, 496, 8128......but what are they?

First, lets talk about factors. Factors of a number are those numbers that divide into it a whole amount of times.

Factors of 10 are: 1, 2, 5, 10

Factors of 18 are: 1, 2, 3, 6, 9, 18

Look at the factors of 6: 1, 2, 3, 6

Exclude that 6 itself is a factor, and add up 1, 2, and 3 and the result equals itself.

A perfect number is such that its proper factors (factor that doesn't include itself) add up to equal itself.

Here is 28:

1+2+4+7+14= 28

We will let you try 496 if you want to give it a go

A history of perfect numbers

A greek mathematician named Euclid discovered the first 4 perfect numbers, listed at the top. This was in around 300BC.

It wasn't until more than 1700 years later that the next perfect number was found, 33550336.

These days, as of 2017, there are 50 known perfect numbers. Not a lot considering how many "numbers" there are. To put it in perspective, the 5th perfect number has 8 digits. The 50th perfect number has nearly 47 million digits. We wont write it down here. This still isn't as big as a googolplex number mind you. Search for our googolplex number blog page.