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What what? Math in my butt!

Ken Melvoin-Berg, Sex Geek ShirtBy Ken Melvoin-Berg


Me and my girlfriend, Sunny Megatron, are geeks. We are actually proud geeks. We don’t have sex, we have . . . SCIENCE!

I love science, D & D, Star Trek, Star Wars, Dr. Who, math, history, and I love sex. I’m a Sex Geek and my T-shirt from Reid Mihalko proudly proclaims that fact. Of all the geeky sex facts I have encountered, this one is by far my favorite: If you haven’t had anal play in a while (a month or longer), you can use the Fibonacci sequence of numbers to approximate the circumference of what can now comfortably fit in your butt.



OK, I know this sounds confusing to most of you. To those that understand this math, the thought of using the Fibonacci sequence to determine anal sizing is a bit unexpected, terrifying, and needs more explanation. Keep in mind, this is only used to go smaller, not larger in the size of anal dildos.

The Fibonacci sequence of numbers starts with 0 and 1, then each subsequent number in the series, adds the previous two whole numbers together. 0,1,1,2,3,5,8,13,21,34,55 and so on. This sequence of numbers when graphed makes the Golden Spiral which is reflected everywhere in nature. You can see this pattern in the shell of a mollusk, leaves on a stem, the shape of a galaxy and the uncurling of a fern. It is everywhere!


Everywhere includes your butt. Now to say your butt is a golden spiral is not exactly correct, however you can use the Fibonacci sequence to figure out mathematically what you can fit into your butt comfortably.

This is an especially useful tool if you haven’t had anal in a while. As we relax and don’t use our anal sphincters for things other than defecation, the muscle shrinks up a bit because the muscle memory gets accustomed to what goes into or out of it. In other words, if you’re not putting a dildo in your ass, it sphincter gets smaller.

To figure out the size of what you can now put in your butt after an anal vacation, you will need two things, the circumference (in centimeters) of the last toy you put in your pooper and the Fibonacci sequence. When you have figured out the circumference of the dildo in cm, go to the previous number in the Fibonacci sequence. Then use that number as your new circumference and the object in your butt will fit just fine!

golden spiral rose

Remember, we are rounding for the purposes of our measurements.

Now that you have your info, let’s see a practical example!

Let’s say Pat had a dildo that was about 1 ½” wide in diameter, that would make the around (4.7”) round up to a 5” circumference.

Circumference is determined by multiplying the diameter and multiplying it times Pi. If you don’t know what Pi is, take 22 and divide by 7 and you can use that number to approximate Pi.

But we need to know what that number is in centimeters, so we will multiply it times 2.54 to give us our number in centimeters. That would make the circumference (12.7 cm) or 13 cm. Remember we will round that up to 13 because we only deal in whole numbers in a Fibonacci sequence.

We now know our first number in the Fibonacci sequence will be 13. We will use the number before this in the Fibonacci sequence, which is 8.  For our example this would be 8 cm, divide that by 2.54 to convert back to inches. This would give us a circumference of 3.2”. We then convert the circumference back to diameter by dividing it by Pi and get a measurement of around 1” in diameter for our example.

1. Measure the circumference of the last toy used in your butt in centimeters

2. Find the closest Fibonacci number to that measurement

3. Go back one number in the Fibonacci sequence

4. That number is the circumference in centimeters of what you can comfortably put in your butt

5. Find a smaller anal toy you like (with a flared base!)

6. Have good sex


This is a guest post from contributor Ken Melvoin-Berg
Ken Melvoin-Berg, Sex Geek ShirtKen Melvoin-Berg owns Weird Chicago Tours and the Midwest’s premier S&M Dungeon, The Studio. As a Lecturer and Sexstorian, he is the creator of On The Edge (a lecture/film series on BDSM). In addition to authoring 14 books on various subjects, Ken edits and writes numerous articles on sexuality. He travels around the world teaching kink awareness to various private groups and continually develops new kink-friendly/sex positive classes.
Ken is responsible for the infamous Northwestern University Fucksaw controversy while teaching his class, Networking for Kinky People. Sunny Megatron is his partner in crime and perverted adventures.

3 replies
  1. ClitStop
    ClitStop says:

    I’m geeking out so hard about this right now! I’m taking Teacher’s Geometry this semester. Now every time someone brings up the Fibonacci series, it’s gonna take all of my strength not to talk about this. http://www.sunnymegatron4.com.php56-15.dfw3-2.websitetestlink.com/wp-content/plugins/wp-monalisa/icons/wpml_good.gif


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