/r/theydidthemath

Photograph via snooOG

And they said math has no real world applications

Submission Rules

  1. Proper title tags are required for all posts or it will be removed! The tags accepted are at the end of the sidebar down there.

  2. State clearly what is being or what you want calculated in the title. [Request] posts must have a calculable answer; otherwise, they will be removed.

  3. Give credit where credit is due—include the user who made the calculations in any post you submit: ex. "[RDTM] /u/FragTheWhale calculates...".

  4. For easy and quick math results (ex. How many feet are in a mile?) use Wolfram|Alpha™. Posts containing "simple math" will be removed, as well as requests whose answers are easily searchable online, and any other post at the moderators' discretion. For more abstract math, try /r/math or /r/learnmath.

  5. Posts which seem to be asking for help on homework will be removed. Try /r/homeworkhelp or /r/cheatatmathhomework instead.

Comment Rules

  1. This subreddit has a zero-tolerance policy for hateful or unnecessary language. There is no warning for hate speech of any kind. Rule breaking posts/comments will have a temporary ban that will serve as a first offense "warning". Repeat or egregious offenders will be banned permanently. Reddit's site-wide rules still apply here. Also, don't be a dick.

  2. Do not submit top-level comments in [Request] posts that are not an attempt at an answer or a request for clarification. Jokes or off-topic top-level comments will be removed.

  3. When answering [Request] posts, please cite reputable sources to defend any evidence that cannot be proven using your own math.

Report any spam/rule breaking posts to the mods with the report button. Be sure to include the reason for your report!


LaTeX and subscripts/superscripts

[; e^{\pi i} + 1 = 0 ;]

Superscripts and subscripts are supported in this subreddit, and LaTeX is used here as well. If the above equation looks like garbled code, or for information on how to display subscripts and superscripts, check our wiki page.


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TAGS!

We require title tags. Here are the tags we accept and what they are for. Please keep them at the start of your post.

  • [Request] - Asking the /r/theydidthemath community to do the math for you!

  • [Self] - You did the math and want to share it!

  • [RDTM] - "Reddit Did The Math", linking to a comment or post on Reddit where someone else does the math!

  • [Off-Site] - Use when linking to any site, including Imgur, that is not reddit.com.

  • [Meta] - Non-math posts regarding the subreddit itself. Don't use this unless you really have to.


Sidebar image from Randall Monroe's xkcd

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  3. Non-Request
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  5. RDTM
  6. Off-Site

/r/theydidthemath

1,607,556 Subscribers

1

[Request] How a big a nuke would need to be to nuke Lake Superior on a single go?

Going on the meme "This is exactly why we have to nuke Lake Superior" I am wondering just how big a nuke would it need to be evaporate all the water in there?

When I looked at this, you need about 10^6 J to turn a kg of water into steam. You have about 10^16 liters of water in the lake. The Tsar Bomba was 10^17 J magnitude so you need a bomb releasing ten thousand times more energy than that. Is this roughly correct?

1 Comment
2024/12/05
11:56 UTC

0

[REQUEST] I was I the top 0.001% of listeners. How many people did I beat?

5 Comments
2024/12/05
11:38 UTC

1

[Request] How to determine the "fair share" of damages, if both people are at fault for the destruction and the agreed price and actual value of the object are different?

Note: This is not a law question, but a maths question:

Seller S makes a sales contract with buyer B.
Object (actual value US§100.000) for the price of US§50.000.

Before S can give it to B, the object gets destroyed, because both S and B were negligent - the fault is 30 % buyer and 70 % seller.

If you determine the financial compensation only from the price (e.g. seller pays 70 % of the 50k = 35k to the buyer) or from the object (e.g seller pays 70 % of the actual value 100k = 70k), the solution doesnt really take into account who made a good deal in the first place.

An extreme example:
Actual worth: 10.000
Agreed Price: 100.000

If the contract was fulfilled contractually, the sellers net worth would be +90k, the buyers net worth would be -90k. If the seller is 70 % at fault for the destruction and had to pay 70k to the buyer, the sellers net worth would be -80k (-10k because he lost the object, -70k compensation) which is a ridiculous -170k from what the situation would have been, if the object wasnt destroyed.

I somehow cannot determine a way to calculate a "fair share" if value and price for the object differ, and also the percentage of "fault" for seller and buyer vary, that accounts for who made a good deal in the first place. Any ideas?

1 Comment
2024/12/05
11:38 UTC

634

[Request] How many calories is that?

28 Comments
2024/12/05
10:29 UTC

124

[Request] How long would this actually take?

15 Comments
2024/12/05
09:57 UTC

315

[Request] How much would the cat have to weigh for this to be true?

11 Comments
2024/12/05
09:53 UTC

0

[Request] What are the odds?

As an adult with no mental issues, I always eat my Skittles by pouring them into a bowl and taking two same-color pieces at a time.

To my horror, this always leaves a few stray pieces that don't have a pair. However, yesterday, that didn't happen!

Each piece of the five different colors in the 95g pack ended up having partner and there were no lone strays.

What are the odds of this happening?

3 Comments
2024/12/05
09:51 UTC

2

[Request] what is the smallest circle that could hold every continent?

(edit: it must at least contain a tiny bit of at least one of a

ny of the 7 continents. Any amount counts.)

5 Comments
2024/12/05
09:06 UTC

1

[Request]

Example of cutting squares at an angle.

Hi, Im wondering about this math question I thought of in my head.

Lets say you place a bunch of squares after each other in a row, with the intent to cut them perfectly at a certain angle so that you can remake the squares with the opposite pieces of left and right side. So for the smallest example in the picture to the left, we cut two squares, first square left side is gonna be perfectly connected with second square right side, and second square left side match with first square right side both with the same measurements as they originally were.

We would then proceed to do this again but with more squares. In which my question/request comes in, what is the minimum angle for this to happen, and what is the maximum possible angle and how many squares would it be with the measurement I have given.

EDIT: Updating the question since maximum angle would presumably be close to 90 degree as infinitely close as possible. What would the amount of squares be right before it reaches infinitely close to 90 degree.

Also, added question, what would be the difference in angles for the different amount of squares. 2 squares, 4 squares, 8, 16, 32, 64........

First time posting here so I hope this is explained enough/clearly for you all :)

8 Comments
2024/12/05
08:15 UTC

1

[Request] Assuming no duplicate views, what’s the chance that everyone who watched the GTA VI Trailer is still alive, and how many are probably dead?

2 Comments
2024/12/05
08:09 UTC

28

[REQUEST] Is this true?

45 Comments
2024/12/05
05:55 UTC

2

[Request] Observer height =160 cm, Relative height of object = 350 cm, distance from the object = 5 km. Actual height of object = ?

Edit: The observer and the object are on the same plane.

5 Comments
2024/12/05
05:34 UTC

0

[Request]

How many people did the CEO of united health kill while acting as CEO? If it helps one American dies every 12 minutes due to lack of health insurance.

2 Comments
2024/12/05
05:32 UTC

14

[Request] If we ever get technology to send probes this far from earth, At how much distance would this photo be possible? How much time would it take to get satellite there and recieve the image back?

5 Comments
2024/12/05
05:07 UTC

1

[Request] At what level with Paper Mario be the same level as Mario & Luigi?

https://www.mariowiki.com/Mario_%26_Luigi:_Paper_Jam_level_up_progressions Here is how leveling works in the game.

I grinded to level 7 as Mario & Luigi, before Paper Mario joins. when he joins, he automatically starts at Level 2. At what level will they be the same level

Mario's first 34 levels (to show how it works)

3 Comments
2024/12/05
05:02 UTC

7

[Request] In Steven Universe the entire ocean is suspended as a pillar, before collapsing down to earth, how large of a tsunami would this cause?

4 Comments
2024/12/05
04:24 UTC

7

[Request] how many farts would it take to fill a hot air balloon?

Asking for a friend.

3 Comments
2024/12/05
04:06 UTC

0

[Request] How accurate is the saying “Shoot for the moon. Even if you miss you’ll land among the stars.”

Assume we are only using the human eye for accuracy, what are the odds that if I point and aim at the moon that I will actually land there and if I miss what are the odds I will land on something else?

1 Comment
2024/12/05
03:41 UTC

1

[Request] is it true that it would take approximately 16 SpaceX Starship launches to complete a single mission to the moon?

2 Comments
2024/12/05
03:29 UTC

1

[Request] At what speed does your tires need to be rotating for them to melt the snow instantly

2 Comments
2024/12/05
03:25 UTC

0

[request] how do you get to one with 3 thirds if .3 repeating x 3= .9 repeating how get to the 1

8 Comments
2024/12/05
02:36 UTC

5

[Request] When will we no longer have total solar eclipses?

Given the current angular size of the moon and the sun, and the moon’s slow recession from earth, how many years from now will we no longer see total solar eclipses from Earth?

11 Comments
2024/12/05
01:54 UTC

1

[Request] How many people are listening to the same podcast?

Let’s say I’m driving home from work in a downtown metropolitan area of roughly 1 million people. Let’s say it’s a 20 minute commute with about 10 of those minutes in moderate traffic.

Let’s also assume that I listen to the number 1 largest podcast (the JRE) and he released a 3 hour episode earlier that day. How many people would I drive past that are listening to the same episode assuming uniform distribution of JRE listeners in the US metropolitan city in question?

Is there some sort of formula where you could extrapolate that to other podcasts based off this calculation if you could just get some of their listener stats?

1 Comment
2024/12/05
01:25 UTC

2

[Request] Can anyone identify the speed of the car from the video?

Can somebody calculate the speed of this car based on the video?

Hi guys, I want to see if anybody is able to find how fast the car coming from the right side was going? Somebody I know was hit in an accident and we’re pretty sure the car was speeding. Somebody posted the video on a local group and I wanted to see if anyone can get any rough number on the MPH?

In the video the car slammed on the breaks decelerating as well, so I’m not even sure if you can get the speed. Thanks for anyone that helps!!

Additional info that may or may not help:

  1. The car was a 2016 Nissan Sentra
  2. I don’t know if the angle of the camera can change it but I put a sticker of a standard stop sign as a reference next to the sign in the video and it didn’t seem very off, so?
  3. The coordinates of the place is (32.7419444, -97.4909722) so you can get a street view (it is a bit outdated but you can see the exact house if you turn around.)
5 Comments
2024/12/05
00:54 UTC

1

[Request] Would my hot tub heat up faster without the restricted flow of the intake filter?

I have an inflatable hot tub. Works great but the pump and heater are pretty small. Obviously, in cooler weather it has a harder time getting up to temp and maintaining. Pulling the intake filter off increases water flow quite a bit.

My question is- would the increased flow heat the tub faster, or would the slower flow heat the water more during its longer time in the pump?

I know there are a ton of variables affecting this, so let's make some assumptions. 300 gallons. The temp maxes out at 104F. When it hits 104 the heater turns off until it gets down to 102, then kicks back on. So I assume the heater is working at a fixed temp, just on or off. Photo of model attached.

Different filters would affect flow, so let's assume a 50% decrease.

I could run some tests here but hard to control external temp. Just wondering what the science says. Any input appreciated... including any efficient way to make it hotter!

4 Comments
2024/12/05
00:05 UTC

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