Wednesday, June 13, 2007

Who invented the Equal Sign?

A bit of math trivia for you today. The equals sign = was invented in 1557 by Welsh mathematician Robert Recorde. In his book, The Whetstone of Witte, he wrote, "To avoid the tedious repetition of these words: is equal to; I will set a pair of parallel lines thus, =, because no two things can be more equal.


Here's your question: Perfect numbers are special because they are equal to the sum of their factors. The number 6, for instance, has factors 1, 2, and 3 which when summed equals 6. The next perfect number is 28. Do you know what the third perfect number is?

Hint: It's less than 500.

6 comments:

  1. If memory serves:

    Euclid's formula
    2^(n-1)*(2^n - 1)

    where n is a prime number:

    n=2 > 6
    n=3 > 28
    n=5 > 496

    ReplyDelete
  2. very impressive, Mr. Don. Keep this up and I'll start calling you Dr. Don, or Professor Don.

    ReplyDelete
  3. Looks like you remembered correctly. The answer is 496. Very impressive memory.

    ReplyDelete
  4. Wow, very nice formula. I was just going to go to a site and get the first eight perfect numbers.

    ReplyDelete

Leave your answer or, if you want to post a question of your own, send me an e-mail. Look in the about section to find my e-mail address. If it's new, I'll post it soon.

Please don't leave spam or 'Awesome blog, come visit mine' messages. I'll delete them soon after.

Enter your Email and join hundreds of others who get their Question of the Day sent right to their mailbox


Preview | Powered by FeedBlitz


The Lamplight Manor Puzz 3-D
Are you looking for a particular puzzle, riddle, question, etc? Or do you want to find the answer today rather than wait till tomorrow!
Google