### Science Fact

#### The Perfect Date

Looking for the perfect date numerically? Today is the only day of the year where both the month (6) and the date (28) are different perfect numbers. June 6 is the only other perfect number date on the Western calendar.

A perfect number is any ordinary whole number that equals the sum of its divisors excluding the integer itself (these are called its proper divisors). For example, the divisors of 6 are 1 and 6 and 2 and 3. If we exclude the integer, then add the remaining divisors, we get 1+2+3=6 (the number).

The first four perfect numbers are 6, 28, 496, and 8,128. Mathematicians believe there may be an infinite number of perfect numbers (although they get large very quickly), but they have only proven the existence of 41 so far -- all of them even. While the first four perfect numbers were known to scholars more than 2,500 years ago (both Pythogoras and Euclid worked with them), the most recent perfect number was only proven in 2011. To date, six other potential perfect numbers have been discovered and are awaiting testing. Two of the known perfect numbers were proven by high school students in the late 1970s.

For more fun with numbers, check out the math resources Science NetLinks has to offer.