On a scale of one to 10, how do you rank scales from one to 10?

Such are the questions that come with exploring the number 10. With 2010 in our face for a whole year, we grew curious about why 10 carries particular significance in religion, math, popular culture, sports and biology, not to mention the irresistible and occasionally infuriating urge to rate everything.

Presumptions abound. Take our system of counting in units of 10. It's tempting to think that it's rooted in our having 10 fingers. (The Mayans, by the way, based their counting system on the number 20, but then they usually wore sandals.)

Paul Zorn, a mathematics professor at St. Olaf College in Northfield, Minn., said the word "digit" is related to fingers and toes, "so it certainly seems very natural that there ought to be some connection with our base 10 system and our anatomy." But that logic and a dime still won't buy a postage stamp. Far more ancient number systems weren't based on 10, Zorn said, such as the Babylonians and their base 60 system. Romans, however, thought in terms of 10s even though they used X's.

Credit mathematicians in India for coming up with what math whizzes like Zorn call "modern decimal positional notation" in the ninth century -- which means they added a zero, which enabled numbers to show different orders of magnitude, such as the "ones place," "tens place" and "hundreds place."

(Don't worry, we'll get to Bo Derek in a minute.)

At any rate, this made arithmetic far simpler, and caught on around the world. Ten became a natural way of sorting, rating and scoring. Consider: There are no Top 11 lists, no hotties that rate a 14. Even God kept his commandments to a tidy 10.

Which leads us to:

The top 10 uses of the number 10 1. Level of Bo Derek's hotness in the 1979 movie, which led to "a perfect 10" forevermore denoting the prettiest, sexiest, hottest, blah, blah, blah.

ø 2. Nadia Comaneci's perfect Olympic score -- the first ever awarded -- on the parallel bars in 1976 (back when a perfect 10 meant skilled).

3. Sum total of the rules you need to keep to gain salvation, as given to Moses.

4. Number of fugitives that the FBI wants most of all.

5. Bowling pins needed to score a strike. (More on this in a moment.)

6. Top playmaker on a soccer team -- think Pele, Maradona, Beckham (right).

7. Counting down from 10 enables NASA to launch rockets and New Year's Eve revels to begin.

8. Counting up to 10 before speaking cools the temper and enables your kids to still appear adorable.

9. Footage of the metaphorical pole that keeps distasteful or dangerous objects at bay -- think raw oysters, the health care debate, Lindsay Lohan.

10. Helps organize lists such as this one.

Wait! There's more!

Longtime Vikings fans know that quarterback Fran Tarkenton wore No. 10 as he scrambled his way to three Super Bowls with the team. We'll say nothing more.

In addition to the 10 Commandments in the Judeo-Christian tradition, God also sent 10 plagues upon Egypt to convince Pharaoh to free the Israelite slaves, and believers are asked to return 10 percent of their earnings to the church.

No wonder then, that 10 is considered a divine number, signifying that something has been completed over the course of time, whether a decade, a century or a millennium, according to numerologists such as Jean Wallis of Minneapolis.

Wallis said the year 2010 is especially auspicious among numerologists, for whom 2010 actually is all about the number three.

"When there are a series of numbers, we always add them up," Wallis said. So two plus zero plus one plus zero equals three.

Three is considered a birth number, Wallis said, "a gateway to all newness." While numerology always reduces series to a single number, 10 has a special significance because of the presence of the zero.

"'1' would be the number, but when backed by a zero, it's backed by the divine," Wallis said, "which means we'll get a lot of help from the other side, shall we say? Whatever people want to call that force that unites us all -- whether you call it electricity or God -- something keeps it going and we can feel supported as individuals. That's when we come into the number 10, and we are always seeking the awareness of that connection."

This all sounds very positive, but there are challenges, Wallis warned. "All this brouhaha in the world right now is because we don't have the understanding of where things are going to land as we reorganize into a new style of leadership," she said. "The challenge is believing it's good news even when it doesn't feel good. When it's our house on the block that's foreclosed, it's hard to believe it's a positive step. But 10 automatically restarts a cycle; it's an automatic new beginning."

Now, before we wrap up, a brief return to the role of 10 in bowling:

Zorn said that, from a mathematician's point of view, 10 isn't all that interesting a number. "It's not prime, it's not a power of prime," he said. "But it is how many bowling pins there are, and why is that?"

Ten, he went on to explain, "is one of the so-called triangular numbers," meaning that it's the number of dots in an equilateral triangle evenly filled with dots. Because 1+2+3+4 equals 10, there's a natural geometry, which may have influenced how bowlers chose to arrange the pins -- although there's also the story that 10-pin bowling came when enthusiasts seeking to circumvent laws in the 1840s against nine-pin bowling added an extra pin.

Still, aiming at that perfect triangle does make strikes that much more satisfying.

And you score a 10.

Kim Ode • 612-673-7185