## Jokes In Order

*September 10, 2011 at 11:21 pm* *
4 comments *

“Daddy,” said Eli, “there’s a new math joke we need to tell you.”

“Really?” I said. “Where did you hear this joke?”

“I made it up,” Eli said.

“Well, then, let’s hear it!”

What did 0 say to 10?

Nice one!

Okay, so maybe it’s not a knee-slapper… but I still think it’s pretty cool that my 4-year-old son created a math joke.

I especially liked that he made up his joke about 10 on the 10th of September; more specifically, on the sequential date 9/10/11. Here’s a joke about sequences:

Being without you is like being a metric space in which a Cauchy sequence exists but does not converge.

The date 9/10/11 is also interesting in Roman numerals — it is IX/X/XI, which is a palindrome. How many other sets of three consecutive Roman numerals, when taken in order, form a palindrome?

Entry filed under: Uncategorized. Tags: eli, joke, math, postaweek2011.

1.JimsMaher | September 21, 2011 at 9:52 amFind all Roman Numerical Palindromes (RNP), of size 3.

IV V VI

IX X XI

IL L LI

I think that’s it.

Did I miss any … well, any less than 100?

I happen to know that there aren’t any RNP size 3 that start at XCIX or above.

CIV CV CVI … no.

DIX DX DXI … nope.

MIL ML MLI … none of these are palindromes.

Here’s a proof for the nonexistence of three-consecutive RNP beginning at 99:

Values above C, as written, begin with C, D, or M.

The only values that end with C, D, or M are congruent to that base,

(i.e. CC or D or MD, etc.) which are also congruent to C for all cases.

Any value consecutively preceding a value congruent to C contains IX (+9).

Any value consecutively following a value congruent to C does not contain XI (+11).

No value congruent to C contains X or I, in any order.

Therefore, no values above 100 written in Roman Numerals are palindromes.

∎

– Are there any RNP of more than three consecutive values that contain C, D, or M?

– I’m not one for numerology, but the idea of palindromes made consecutively within numerical systems … binary is full of palindromes, less so in Base Ten; in fact, unless I’m mistaken, ignoring negative numbers, there are no BTP’s.

2.venneblock | September 21, 2011 at 3:02 pmJims, I don’t think IL is an acceptable representation of 49. The rules for Roman numerals allow subtraction only when the subtrahend preceeds a minuend no more than ten times larger. Hence, the only acceptable representation of 49 in Roman numerals is XLIX.

Funny story along those lines, though… my son saw a sign that said, “You must have a valid ID to use your Guest Rewards card.” He asked, “Daddy, what is ID? Is that 499 in Roman numerals?”

3.JimsMaher | October 4, 2011 at 2:08 am“no more than ten times larger”

By that rule, the Packers won two Super Bowl’s this year.

XLV and VL.

Also, I may have been LI-ing about IL … I’m not a Chicago Bears fan after all. Chicago, IL … they’re in the same division as the Green Bay Packers.

That’s a long way to travel for a joke, I know.

4.Gregory Koch | January 10, 2013 at 4:30 pmhttp://en.wikipedia.org/wiki/Roman_numerals cites the Python Cookbook to say that I can be subtracted from V and X only, X from L and C only, and C from D and M only, while V, L, and D can never be subtracted. (So 450 would be CDL, not LD), for example).

So it will be Super Bowl XLIX.

And here’s an amusing article about the NFL’s plans to successfully market and sell t-shirts with a big fat “L” on them in 2016 for Super Bowl L

http://online.wsj.com/article/SB10001424052970204652904577197312698087518.html