But no where close to the solution. You might remember the original observation and some progress to this problem from my prior posts.

This evening, I sat down in our balcony with Jay Jay and a cocktail when I noticed that there was a crew of two people in the post office yard. And in a few seconds later realized that they were painting the vans. Especially the roofs.

I got excited. Maybe finally I will crack this problem?

But there was something very incongruous about their painting. They had not covered up the windshield!! I was wondering how were they preventing the white paint from getting all over the glass?

The curiosity and the possibility that I might finally know the answer to the roof rust problem got the better of me. Put Jay Jay inside the house and walked up to those guys from a side entrance.

The two gentlemen could not have been more surprised by my question!! A very interesting conversation happened then.

First thing, I learnt is that they were not painters. They were simply cleaning the vehicles. And that was not rust – it was mold!! They see this mold in all the mail delivery vans. And they agreed that it always forms on that particular edge. But neither had any clue why.

Oh! so close!!!

As I was walking out, I saw a USPS gentleman trying to put something in another van. I walked up to him and made friends with him. He first apologized that our house looks into the USPS yard. I assured him that it gives me endless joy watching the vans and trucks come in and the workers milling around.

And then I asked him the all important question. You know what he said? He said that from the upper deck, it had noticed that pattern too but never knew why. And he had not spent much time thinking about it anyways. Then both of us stepped into one vehicle to see if we could see anything from the inside. Absolutely no clues!!

He did teach me something. He explained that these were 25 year old Grumman LLVs. And that USPS is switching over to newer vehicles by Oshkosh. Came back home and read up about it. There are fascinating facts out there about these vehicles.

But not a word on why mold grows on only one edge of them.

The endeavor continues!!

Do you remember the last two curiosity questions I had posted on the postal vehicles? The one about why one side of the postal vehicles’ roof is always rusted and the other one about why some of them have steering wheels on one side while the others have it on the other side?

Well, hearing the responses from you all on the second one, we might be closer to solving the first one.

For the second, we have logically concluded that the steering wheel is on the “wrong” side only if the vehicle is meant to deliver mail door to door. That makes sense. The mailboxes are on the right and the driver does not have to get out every single time (not to talk about seat belt on and off). The ones that had steering wheel on the “right” side clearly was being used to transfer mail between post offices or purposes as such.

This morning, while having tea in the patio, I tried to see if the roof rusting matched a pattern I was wondering about.

LO AND BEHOLD!! IT DID!!!

Look at the picture. There are three vehicles that have no rusting on the roof. Look closely at those vehicles – they are the different looking vans that are NOT used for door to door delivery. And look at the door to door delivery vehicles. Each one of them have that pattern.

So, this HAS to do something with the requirements on a vehicle for door to door delivery. I know they do not have any HVAC. The windows are always open for constantly flinging the mail or putting the mail in the mailbox. I have even seen table fans in these vehicles to cool down the drivers.

So, what is it about windows being always open that might have something to do with the rusting?

This is where I am starting to think that Nick Kules might be on to something… that the way the drainage on the roof is designed might have something to do. Could it be that there are ridges so that after a little rainfall or water accumulation, the water does not drip down the window and potentially wet the mail? And that is why the stagnated water rusts out the roof?

Then why not on the driver’s side also?

I HAVE to crack this problem.

Need you all to pitch in with your combined imagination and analytical powers.

Having a house in front of the post office is one of the more enjoyable features in my new living. Sitting down in the balcony early in the morning with a cup of tea, I can spend hours watching the postal folks get busy with their day.

As always, there are curious questions I have that I have found no answer. You may remember the one about all postal vehicles having rust on the front side of the roof on the non-driver’s side but nowhere else. Never figured out why.

In fact you can see that in all the vehicles lined up agains the wall in the picture!

Today, I noticed something else intriguing. Early morning a tow truck showed up with two postal vehicles. This is common for Mondays. I assume they had gone for maintenance over the weekend.

Look at which side the driver is sitting!!! It is the opposite side of postal vehicles (but in alignment with all other vehicles)!!

So when do postal vehicles have steering wheels on the “normal” side and when do they have on the “other” side?

A couple of days back, Matt, Sunjay, Hunt and myself were Slacking about Sunjay’s use of the punctuation mark “?!”. Which got me to read up on punctuation marks that are rarely used these days.

See how many of these you might now. First name the punctuation mark and see if you can guess when it is used.

The ninth one looks like slanted in my handwriting. I meant to draw a straight line. (You have it on your keyboard as “|” )

12 years back, on my way back home from DC, I used to post a puzzle almost every week. Doing the same today.

A little background… This week, in Chicago, Deval gave me a little gift. Apparently, she was in a store that sells calendars and came across a calendar that a math problem for each day. Somehow I came to her mind!!

And this is the first problem I saw on the cover page.

You remember mod right? It is the remainder remaining after you do a division. So 27 mod 6 would be 3.

The puzzle is:

15¹¹³ mod 113 = ?

I found this while reading some website.

As you see, there is a quadrant and within that there is a circle that touches one axis. The line that is parallel to that axis and is a tangent to the circle is 12 cm.

Question is what is the area that is shaded? (basically, the quadrant area sans the circle)

… but here is one if you want to try.

A and B are identical squares. C and D are squares too. The only measurement you are given is that the line going from where A&B meet to where C&D meet (the dotted line) – and that is 4 units. The question is what is sum of the areas of C and D (shaded areas).

From the picture you may be able to see that it is raining heavily. Sitting in my balcony, I can see the rain drops hit the parking lot surface in the light that is reflected there.

Here is a question that flashed thru my mind. How many raindrops does the earth get? Millions? Billions? Trillions?

To get started, let’s say it rained in Alpharetta (say 25 square miles) this morning for about 4 hours. How many raindrops did we get?

First take a guess. Just guess how many zeroes (or digits) will be there in that number.

Now, try to do the math. Make whatever assumptions you need to. (And they will differ from person to person). What number do you get? How many digits?

How close were you?