The factors of six are 1, 2 and 3 (not including six itself)
Add up these factors and you will get six:
1+2+3 = 6
Six is a perfect number as it is the sum of its factors. Can you find any other perfect numbers?
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The next perfect number is 28 (= 1 + 2 + 4 + 7 + 14)
The next perfect numbers are 496 and 8128
Then 33550336, 8589869056, 137438691328, 2305843008139952128, 2658455991569831744654692615953842176, 191561942608236107294793378084303638130997321548169216.
I bet you didn't get those!
Teacher, do your students have
access to computers? 

Here is the URL for a concise version of this page without comments or answers.
Here is the URL which will take them to a differnt type of number puzzle.
Related to perfect numbers are amicable numbers. Two numbers are amicable if the sum of the proper divisors of the first is equal to the second and vice versa. Sociable numbers form a closed sequence where the sum of the proper divisors of one number is equal to the next number in the sequence. The sum of the proper divisors of the last term of the sequence is equal to the first number. (A proper divisor of a number is a positive factor of that number other than the number itself. For example, the proper divisors of 10 are 1, 2, and 5.)