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#1 Re: Puzzles and Games » Sort of like Sudoku » 2016-06-14 00:02:07

Those constraints still yield multiple solutions, but I don't know how many there are in total.

Here are twelve of them:

#2 Re: Exercises » Quickies #3 Assorted Math » 2016-06-08 01:39:08

I could've saved a lot of time if I'd thought of doing the same!

#3 Re: Puzzles and Games » Starter puzzle on this site "12 Days Of Christmas" » 2016-06-07 20:55:37

True! up

A similar program in BASIC:

    WHILE d<13
    PRINT ppd

And...welcome to the forum! smile

#4 Re: Exercises » Quickies #3 Assorted Math » 2016-06-07 20:16:59

Hi Bobby;

Did you deliberately misconstrue the intended meaning of my unintentionally ambiguous statement? If so, I think we're on the same team! smile

I meant overlook as in fail to consider.

I don't know enough M to go the way of proper structure most of the time, so when it occurs to me to use Flatten, I do.

#5 Re: Exercises » Quickies #3 Assorted Math » 2016-06-07 16:09:57

'Flatten' is something I often overlook until I've exhausted all other ways of successfully performing an operation on nested elements.

#6 Re: Exercises » Quickies #3 Assorted Math » 2016-06-07 16:03:42

Ah...I see your problem! You need them!! wink

#7 Re: Help Me ! » Geometry Proof » 2016-06-07 16:01:25

I'm expert at initiating 'first time' events, like:

- asking a whitegoods service technician why my machine is making an xyz noise: "Sorry, sir, but we've never heard of our machines making an xyz noise before." (maybe I should practise up on making xyz noises over the phone, or send them an mp3 recording of said noise);

- asking Customer Service if there's a fix for this or that: "Oh, we've never been asked about this or that before. Hang on a minute". That's when you discover that your understanding of the length of time a minute takes is way off the mark!

#8 Re: Exercises » Quickies #3 Assorted Math » 2016-06-07 15:37:25

You have your specs on inside out!

#9 Re: Help Me ! » Geometry Proof » 2016-06-07 15:35:06

Oh, I see...the word in those posts, not my search word. I sent MIF all the facts that I remembered...

#10 Re: Exercises » Quickies #3 Assorted Math » 2016-06-07 15:29:32

It certainly looks the part, and using it probably leads people into thinking that I know what I'm doing! big_smile

#11 Re: Exercises » Quickies #3 Assorted Math » 2016-06-07 15:06:02

Just stumbled across that. The idea popped into my head that there might be a symbol for product as there is with sigma for summation, and so I started looking.

#12 Re: Help Me ! » Geometry Proof » 2016-06-07 15:00:14

The search word was incircle, which gave 25 results.

I was interested in 6 of them, 4 of which (years 2015 & 2016) opened up fine; but 2 (or was it 1? - I don't recall now) of the older ones (year 2014) opened up the 'forbidden access' page.

#13 Re: Help Me ! » Geometry Proof » 2016-06-07 14:44:31

I learnt the hard way. I lost my right arm after the xth click and had to ask MIF to sew it back on again.

#14 Re: Exercises » Quickies #3 Assorted Math » 2016-06-07 14:42:18

My symbolic version of the factorial method has about 15 fewer keypresses than yours.

#15 Re: Help Me ! » Geometry Proof » 2016-06-07 14:31:33

Yes, I knew about censored words, but this one threw me because all I did was click on a search result.

But I clicked it several times, just in case there was some hiccough. If I'd only clicked once (or twice? or thrice?) I may not have been locked out.

#16 Re: Exercises » Quickies #3 Assorted Math » 2016-06-07 14:27:09

That's a neat way of doing it!

I'd wanted to make a table and do a Times@@ on it, but couldn't get the table working.

#17 Re: Help Me ! » Geometry Proof » 2016-06-07 14:11:45

I'm deeply honoured to have joined your club - unintentionally!

#18 Re: Exercises » Quickies #3 Assorted Math » 2016-06-07 12:50:27

Hi Bobby;

Did you look at the M code in my previous post? I added the 'DivisorSigma' function to the list, having come across it in M's 'Suggestions Bar' that pops up when you click somewhere on the output screen. Would've saved me the time working out how to sum divisors...but I don't really mind learning something new. smile

#19 Re: Help Me ! » Geometry Proof » 2016-06-07 12:37:45

This is a popular problem! smile

Other posts that may help:

- thread opened by Enshrouded_, 23rd Sep 2015
- thread opened by championmathgirl, 9th June 2015
- thread opened by SPARKS_CHAN, 30th Jan 2015

I haven't checked out the solutions, but Bob Bundy posted there and he always gives good advice.

Warning! Be careful with threads on this topic earlier than the three above (there are also two threads from 2014). I got locked out from the forum overnight after clicking multiple times on a 2014 post that opened up a 'forbidden access' page. MIF knows about it now, and unlocked me. If you do get a 'forbidden access' page after clicking on a post, don't click that post again.

#20 Re: Exercises » Quickies #3 Assorted Math » 2016-06-06 11:20:09

Hi thickhead;

I saw the factorial answer first and then checked it with the same diagonal method as yours.

From there I extracted the primes as
, checked that against my factorial answer, and then applied (a+1)(b+1)(c+1)(...+1) to the exponents to get 770515200.

And I also tried it in M, in various ways:

M gave an error message that I don't understand, but otherwise it all works.

#21 Re: Exercises » Quickies #3 Assorted Math » 2016-06-06 02:08:34

Hi thickhead;

I get 770515200, based on the same product as Bobby's, which I got from:

#23 Re: Puzzles and Games » Sort of like Sudoku » 2016-05-24 10:20:37

Hi thickhead;

phrontister wrote:
patchy1 wrote:

Numbers can't repeat in any given row or column (like sudoku).

That would only apply to the eight odd-lettered/numbered rows and columns, I suppose.

patchy1 wrote:

Yes that's right

Row F is one of the six even-lettered/numbered rows and columns, so repeats in that row are allowed.

'4' is also repeated in column 6 of post #12's solution, but as that column is even-numbered, it is allowed too.

#24 Re: Help Me ! » Modular arithmetic » 2016-05-24 01:22:22

Hi all;

This formula works (it's based on the one given by noelevans in post #2 of the other thread for this puzzle):


n = a 3-digit number
r = n's row number (first row = 0)

Table 1, row 0:
Mod(Mod(856,856-0),9) = 0

Table 2, row 8:
Mod(Mod(539,539-8),9) = 8

Table 3, row 9:
Mod(Mod(273,273-9),9) = 0

Table 3's letter values:
A = 0
B = 1
C = 2
D = 3
F = 4
G = 5
H = 6
J = 7
K = 8
L = 0

I had tried to solve it with base 9, but couldn't do it. However, that inspired the Mod 9 addition to noelevans' formula.

#25 Re: Help Me ! » Modular arithmetic » 2016-05-23 17:45:41

This puzzle was posted by patchy1 way back on 8 July 2012, here.

From that thread's first post:

In the 18 examples in the first two boxes below, a simple arithmetic operation on the 3-digit numbers leaves you with the 1-digit numbers. I need to figure out the required simple operation, and translate the ten numbers in the third box into the lettered solutions.


A giveaway clue - there can be no 9's in the solution.

The arithmetic operation has two parameters - the given number and another number that is not the same for every case
- and you are looking at it.

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