Last month there was a story on BBC.com entitled “Spain’s new submarine ‘too big for its dock'” (https://www.bbc.com/news/world-europe-44871788)

The main part of the story is that Spain’s new non-nuclear submarines were built too large for their docks. (Hmmm. Guess that was obvious just from the headline.)

The reason the submarines were too large is that they were redesigned to be bigger than originally planned.

The reason they were designed to be bigger than originally planned is that they were heavier than expected, and so the buoyancy was off, which for submarines is pretty important. By the time that was discovered it was easier to increase the buoyancy by increasing the volume than by decreasing the weight.

And finally: The reason that they were so heavy is that someone put a decimal point in the wrong place. According to the article “Navantia gets US help to fix overweight sub” by T. Kington (from http://www.defensenews.com in June 2013, but apparently unavailable now), the former director of the Office of Strategic Assessment at Spain’s Defense Ministry, said **“I have been told it was a simple matter of someone writing in one zero when they should have written three.”** I put that in bold, because that small mistake, just twice zero, has taken years and ~~millions~~ billions of euros to (still not fully) rectify. The contracts for four subs were signed in 2004, the first of the subs was nearly done in 2012 when the mistake was discovered, and now it looks like the subs are all dressed up with nowhere to go. Poor subs – we look forward to a mathematically successful end to this story.

*The submarine photo isn’t actually an S-80: it’s a public domain photo of the USS Chicago (U.S. Navy Photo by Photographer’s Mate 1st Class Kevin H. Tierney. Edited by ed g2s). *

I had been so distracted by the descriptions of triangular cupcake liners that I didn’t order any, but certainly those would have made for more equally shaped triangles and a crisper looking design. This was made by baking a 9″×13″ cake, cutting it into 3 long strips, and doing a zigzag pattern on each to get 9 equilateralish triangles plus a bit extra. Now I just need an extra-large platter for serving, because we are SO having this again sometime…

]]>

Amazon has trouble with triangles.

Granted, I only saw oddities on two pages, but since that’s 100% of the pages I looked at, it was still a pretty high percentage.

**Exhibit #1: ** Triangle is now a color:

**Exhibit #2: ** Triangles have a diameter:

Of course, triangles do in fact have a diameter, since there’s a maximal distance between points (which turns out to be the length of the longest side). So presumably these are 2″ per side, and Amazon gets bonus points for an unnecessary use of Diameter. I admit, though, that part of me thinks that what they called “diameter” was really the distance from a vertex to the opposite side, because from a visual perspective I think that seems the most like the diameter of a circle. That would mean that the actual side length was (2/√3)*2″, or about 2.3″. The other cupcake liners were 2″ to a side at the base and 2.4″ to a side at the top, which means that either number would be consistent even if these were the same size.

So in the end, I’m not sure of the answer. What I am certain of, however, is that the Sierpinski approximation cupcake is an awesome idea, and should become a reality as soon as possible.

]]>

There’s an article about it here, but it doesn’t lessen the confusion at all.

(The reference to the question of which is closer, the West Cost or the Moon, is a reference to a discussion from a year ago.)

]]>Back in November of 2007, the National Lottery in the United Kingdom had a new scratchoff ticket for their “Cool Cash” Lotto. The idea behind the game was the a person would scratch to reveal a specific temperature — say, 15º — and would then scratch to reveal three more temperatures. If any of these three numbers was lower than the Chosen Special one (15º in this example), then the person won a prize. Hooray!

But this was in the UK, which uses Celsius, and negative temperatures are pretty common in the winter. So the target temperature might be something like –7º, and the three additional temperatures might be –6º, –5º, and –4º. From a mathematically correct point of view, that’s not a winning ticket because all the numbers are above –7º. But people who focused on the numberals 6, 5, and 4, all of which are less than 7, thought they’d won.

It took but a day for this to become a problem, and after no small amount of confusion on the part of customers and shopkeepers, the tickets were pulled. They had lasted less than a week. Lottery we hardly knew ye.

*For more details, including a video, see the article in the Manchester Evening News:*

*https://www.manchestereveningnews.co.uk/news/greater-manchester-news/cool-cash-card-confusion-1009701*

**Double the Celsius, and subtract from it the amount obtained by moving the decimal place one unit to the left. Then add 32 to get the corresponding Fahrenheit.**

For example, with a temperature like 50°C, you’d double 50 to get 100, then from that subtract 10.0 to get 90. Finally, you’d add 32 to 90 to get 122°F.

This is equivalent to the formula

Temp in °F = (9/5) (Temp in °C) + 32.

In particular, if C is the temperature in Celsius, the description to double and the subtract that amount with the decimal place moved describes 2C – 0.1(2C), which is 1.8C, or 9/5C.

It does seem to me to be quicker to compute 9/5C by doubling C and subtracting a tenth of the result than to multiple by 9 and divide by 5 in some order. The conversion isn’t as quick as “Double and add 30″*, perhaps, but unlike that estimation it has the advantage of being exact.

*a formula that always brings to mind the movie *Strange Brew*

*The thermometer is by Bernard Gagnon – Own work, CC BY-SA 3.0. It has Centigrade rather than Celsius at the top, which I found interesting since I remember learning both terms in school*.

This mistake was printed almost a year ago, but it’s still relevant, and math mistakes never go out of style. This was posted by Richard Fuhr, who I believe is the original author.

The author was looking at an article about the Gobi desert in China, which read in part: “Temperatures may vary up to 95°F (35°C) in one day in the Gobi.” It also indicated that the average temperature in winter was -40°F (-40°C) and in the summer could be 122°F (50°C)

The -40°F being equal to -40°C is correct – it’s the only place the two temps have equal numerical designation, and I am a little sad that I’ve never gotten to experience it except in windchill form. The 122°F being equal to 50°C is also correct, and something I have exactly no desire to experience, although it’s still lower than the 129.2°F (54°C) recorded in Kuwait last month. Both of those conversations can be found by using one of the formulas

- Temp in °C = (5/9) (Temp in °F – 32)
- Temp in °F = (9/5) (Temp in °C) + 32.

The issue is that these are temperature readings, not changes in temperature. For a change in temperature, the 32 in either formula will disappear, leaving

- Δ°C = (5/9) (Δ°F )
- Δ°F = (9/5) (Δ°C)

This means that a **variation **of temperature of 95°F would actually correspond to a change of about 52.8°C, not 35°C. And a variation of 35°C would be a change of “only” 63°F, not 95°F. It’s not possible to tell mathematically whether the correct variation was 95°F (53°C) or 63°F (35°C), but looking through The Internet at temperature variations, it appears to me that although either one is possible, the printed variation was likely intended to be 35°C, not 95°F.

*The photo above is by Doron, with a Creative Commons license. Thanks to YG for bringing the original article to my attention!*

]]>

The video is available below, and there is more info at NASA.

]]>(from Brainfreeze Puzzles: Digits 1-9 in each row, column, and square, plus digits 31415926 in each block of pink)

and grab a beverage of your choice

and enjoy. Happy Pi Day!

]]>