Welcome to RadMaths! We will update popular maths problems and discussions to help you learn, think more and advance in Maths.

Science(and programming!) to be included in MadScience :)

*MATHATHON by Percy Jackson*

Mathathon 2020

Mathathon 2021

*list of 1000 primes - FOR NORMAL USERS*

*list of primes to a million(78498 primes) - FOR CODERS (aware:may take 1 minute to load)*

*LATE EVENTS:*

approximating a slice of pi

approximating a slice of pi - remade

Finding number of prime factors

**Problems:**

*Alice Smith*

*Zakir Husain*

- Pre-RMO questions
- The e-day quiz
- It’s Mathematics Olympiad series

1,2,3

*Jeff Giff*

- Dr Fiendish series

1,2,3,4 - 13-year-olds’ homework in China(the hard problems) set

- Dr Fiendish series
*Aryan Sanghi*

*Valentin Duringer*

- Dynamic Geometry series

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48, 49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91, 92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,

129,130,131,132,133,134,135,136,137.

Notes have been published on this series:see discussions part.

- Dynamic Geometry series
*Nihar Mahajan*

- Calculator is for the dull series

1,2-credits to a former brilliant member,3-credits to Zakir Husain,4-credits to Zakir Husain,5-credits to Zakir Husain

- Calculator is for the dull series
*Aman Rajput*

*Tomislav Franov*

**Discussions:**

*Zakir Husain*

*Yajat Shamji*

- Recurring proof notes (See Recurring decimals).
- Number spy challenges

1,2

*Gandoff Tan**Vinayak Srivastava*

*Páll Márton (A Former Brilliant Member)*

*Jeff Giff*

*Chew-Seong Cheong*

- On Dynamic Geometry series

On Q32,77,89,94,98, On Q80,85,90,99,105, On Q96,101,106,109,111,112

- On Dynamic Geometry series

**Formatting:**

*Brilliant*

*Percy Jackson*

*Páll Márton (A Former Brilliant Member)*

No vote yet

1 vote

Easy Math Editor

This discussion board is a place to discuss our Daily Challenges and the math and science related to those challenges. Explanations are more than just a solution — they should explain the steps and thinking strategies that you used to obtain the solution. Comments should further the discussion of math and science.

When posting on Brilliant:

`*italics*`

or`_italics_`

italics`**bold**`

or`__bold__`

boldNote: you must add a full line of space before and after lists for them to show up correctlyparagraph 1

paragraph 2

`[example link](https://brilliant.org)`

`> This is a quote`

Remember to wrap math in`\(`

...`\)`

or`\[`

...`\]`

to ensure proper formatting.`2 \times 3`

`2^{34}`

`a_{i-1}`

`\frac{2}{3}`

`\sqrt{2}`

`\sum_{i=1}^3`

`\sin \theta`

`\boxed{123}`

## Comments

Sort by:

TopNewestQuiz

@Vinayak Srivastava @Mahdi Raza @Percy Jackson @Jeff Giff @Aryan Sanghi @Yajat Shamji

Log in to reply

It doesn't work.

Log in to reply

But it is working in my PC Right now!

Log in to reply

Log in to reply

Nice and very simple quiz

$10/10$ for the interesting thought for making the question

Log in to reply

Ah but I can’t access it in mainland China :P

Log in to reply

e

A new one!

Log in to reply

Now it started! @Vinayak Srivastava @Mahdi Raza @Frisk Dreemurr @Aryan Sanghi @Yajat Shamji @Siddharth Chakravarty

Log in to reply

Log in to reply

Log in to reply

$b_{n+1}=b_n(\frac{1}{a}-n)$ $=b_{n-1}(\frac{1}{a}-(n-1))(\frac{1}{a}-n)$ $=(\frac{1}{a}-n)(\frac{1}{a}-(n-1))...(\frac{1}{a}-1)\frac{1}{a}=\prod_{k=0}^{n}(\frac{1}{a}-k)$ $\Rightarrow b_{n+1}=\prod_{k=0}^{n}(\frac{1}{a}-k)$ $\therefore b_{n}=\prod_{k=0}^{n-1}(\frac{1}{a}-k)$ $\Rightarrow b_na^n=a^n\prod_{k=0}^{n-1}(\frac{1}{a}-k)$ $=\prod_{k=0}^{n-1}a(\frac{1}{a}-k)$ $=\prod_{k=0}^{n-1}(1-ak)$ $\therefore\lim_{a\to 0} b_na^n=\lim_{a\to 0} \prod_{k=0}^{n-1}(1-ak)$ $=\prod_{k=0}^{n-1}\lim_{a\to 0}(1-ak)=\prod_{k=0}^{n-1}1=1$ $\therefore\lim_{a\to 0}b_na^n=1$ $\therefore \red{\lim_{a\to 0}\frac{b_na^n}{n!}}=\frac{1}{n!}$ $\lim_{a\to 0}\sum_{n=0}^{\infty}\frac{b_na^n}{n!}=\sum_{n=0}^{\infty}\red{\lim_{a\to 0}\frac{b_na^n}{n!}}$ $=\sum_{n=0}^{\infty}\frac{1}{n!}=e$

Solution of second last one (with standard notations) :Log in to reply

Log in to reply

Could any of you make this a quiz or problem set on brilliant? Thanks!

Log in to reply

Sure

Log in to reply

@Jeff Giff - You can use buttons in RadMaths to make it more rad. See my note Buttons to learn button formatting :)

Log in to reply

I used it in anther note :) I don’t think it is necessary to add buttons here :)

Log in to reply

Hi @Tomislav Franov , your problem set has been included to this note! Good job! :)

Log in to reply

Hi, thank you so much!!!

Log in to reply

Nice, @Jeff Giff

Log in to reply

What about my Recurring Proof Notes? You think they are useful to your note, @Jeff Giff?

Log in to reply

@Jeff Giff- Try my A Pre-RMO question! series, Math also Fails! series.

Log in to reply

That's a definite one for @Jeff Giff to try - the Pre-RMO questions.

Also, RMO stands for...?

Log in to reply

By the way, try this for Math Also Fails - $e^{i\pi} =-1, (e^\pi)^i =-1,$ then $i=\log_{e^\pi} -1?!$

Log in to reply

No actually, definition of log clearly states that $log_ab$ is defined only when

$a \gt 0 and a \neq 1$

$b \gt 0$

Log in to reply

Well it is correct, and not surprising if you know the Taylor series of $\ln$ and this

Log in to reply

If you want a big and detailed explanation you can ask for that (can even write a note!)

Log in to reply

Oops.. that’s logarithm for negative numbers :/

Log in to reply

Good idea! I’ll add them :)

Log in to reply

@Jeff Giff, Thanks for the mention for my $\LaTeX{}$ Guide but, it is a work in progress and I can suggest you better ones - Daniel Liu's Guide and Hamza Anushath's Guide.

Log in to reply

Ok! Thanks!

Log in to reply

Thanks for the mention of Mathathon 2020 too!

Log in to reply

And please add mine too @Jeff Giff

(I am Hamza Anushath)Log in to reply

@Hamza Anushath - He still didn't add your Latex note, LOL

Log in to reply

@Percy Jackson @Jeff Giff

Yeah, it has been two weeksLog in to reply

Log in to reply

@Hamza Anushath

Mathathon started, start posting solutionsLog in to reply

@Percy Jackson

Yeah, if I post solutions for past questions, will I still get pointsDeduct five points from the total due to late submission if you'd like as well

Log in to reply

@Percy Jackson...

Cuz I didn't see the Mathathon problems till just nowLog in to reply

Log in to reply

@Percy Jackson!

ThnxLog in to reply

Try my When two lines meet series, it is a series of hard questions for learning to solve questions using graph. Is this useful for your note?

Log in to reply

@Jeff Giff Add this sreies also, of @Aryan Sanghi

Log in to reply

Thanks a lot @Zakir Husain

Log in to reply

@Jeff Giff for adding this in the note

Thanks toLog in to reply

Log in to reply

@Jeff Giff Also try to add polyfon series by @Aryan Sanghi

Log in to reply

Yes,thanku. I'll try to make the polyfun series more vast by adding more problems to it.

Log in to reply

@Jeff Giff- Kindly mention this note instead of my feed for Pre-RMO question series.

Log in to reply

👌 OK!

Log in to reply

@Jeff Giff, could you $\color{#333333}\text{add my note}$ too as a $\LaTeX$ guide, it has many new facts and features which may only have been mentioned by me

Log in to reply

Click the $\text{add my note}$ to access my note @Jeff Giff

Log in to reply

@Jeff Giff, if you need anything from me, check out my profile and choose the series (i.e. if you choose one problem, you have to have the rest of the problems with that title.)

Log in to reply

@Jeff Giff - Kindly add this in RadMaths ''Late Events''

Log in to reply

@Jeff Giff Thanks!

Log in to reply

Check this out, @Páll Márton :)

Log in to reply

Thank you!

Log in to reply

@Jeff Giff What about this?

Log in to reply

Wowie!!!!!! RadMaths has become even better! Good work @Jeff Giff! You'll have to organize it a bit though, like removing the Mathathon as it is over, adding more space between 2 different series, etc.

Log in to reply

@Jeff Giff it is Vinayak Srivastavsa not

Yinayak@Vinayak Srivastava ?Log in to reply

Yes @Jeff Giff!

Log in to reply

Uh oh. Typo ^@^

Log in to reply

@Jeff Giff, check out this:

Magic Square Connections Study

Log in to reply

@Jeff Giff you might like to add my Coordinate geometry series. All of its questions are popular and level 5. :)

Log in to reply

The link is level 4 actually lol

Log in to reply

Yes, this question didn't live to the expectations, but it's atleast popular. :)

Log in to reply

Log in to reply

Log in to reply

@Jeff Giff, I think the

actualPRMO discussion is this, so please change the link, that one has only sample questions. :)Log in to reply

very nice collection. thank you

Log in to reply

Hey everyone! I just found a way to nest buttons!!! All we have to do is to quote in a button and make a button in the quote! Only we can’t nest tables :( @Frisk Dreemurr , @Yajat Shamji

Test: (Failed)

Log in to reply

Páll Márton would love this awww... but he is removed :(

Log in to reply

You used > to make a quote right

Log in to reply

How did you make it, I can create the nested button but can’t hide stuff in it

Log in to reply

Log in to reply

Is it okay if I remake this note to make it more... accessible? I will give credit + link to this note as well if you do

Log in to reply

Ok :) but a better way would be to link this note in the daily problem solutions :) or would you just want the code for this note?

Log in to reply

You see, num IC has accessed this note from my daily solution :)

Log in to reply

Look:

Log in to reply

@Jeff Giff, the deed is done. Check out my latest note!

Log in to reply

@Jeff Giff mention[10101485:Jeff Giff]

Log in to reply

Log in to reply

here

Check my new mentions page then,@Frisk Dreemurr mention[10427613:Frisk Dreemurr] (I need to add your mention Id)

Log in to reply

Log in to reply

Line 25 may be my worst creation (holy cow I didn’t click enter) :P

Log in to reply

@Jeff Giff Kindly add this

Log in to reply

Done :)

Log in to reply

@Jeff Giff Add

this in boldLog in to reply

@Jeff Giff Can you add these?

Calculator is for the dull - 5, Calculator is for the dull - 4, Calculator is for the dull - 3,

Calculator is for the dull - 2,Calculator is for the dull - 1, It's Mathematics Olympiad! - 3, It's Mathematics Olympiad! - 2, It's Mathematics Olympiad! - 1, Trigonometry Everywhere - 2, Trigonometry Everywhere - 1These are not by me (those in bold)Log in to reply

@Jeff Giff ????

Log in to reply

@Jeff Giff What about "It's Mathematics Olympiad" ? and "Trigonometry Everywhere" ?

Log in to reply

Log in to reply

Oh I wasn’t noticed! Now I see :)

Log in to reply

Thanks for all that!

Log in to reply

Have you edited the note? I am not able to see them right now...

Log in to reply