Math Is Fun Forum

Hi Bobby,

I don't know if you're still having a crack at this, but NOHOW doesn't really seem to have hit the spot on MIF.

I'd like to try to get some discussion going about it to see others' strategies and if they differ from mine - which they probably will. I used modern tools to help with my solution of this 1966 puzzle and I doubt that I followed the author's intended strategy.

I'm thinking of posting it on a couple of other puzzle sites and in readiness for that I've deleted the great big hint I gave earlier. It really was far too great big a hint because it leads to a solution too obviously, thus influencing any thoughts on developing a strategy and consequently diminishing solving satisfaction.

Finding a way to make a solid start with this frustrating puzzle was, for me, half the fun, and I don't want to spoil it for others.

IMHTBO, NOHOW's a terrific puzzle. It only needs basic high school maths knowledge, but I found it to be a very enjoyable and satisfying teaser. A good calculator would come in handy, and certain components of the puzzle are very suited to using modern computing aids.

Do you know of any puzzle sites where this type of puzzle, and also two of my other unpopular puzzles - Little Pigley Farm and Joan's telephone number & my YOB - might get more acceptance?

Hi soha,

On my computer your status (under your avatar) now shows you as being "Offline", which to me indicates that your logout is working.

Hi Bobby,

Nice one! And a profound statement by Henry David Thoreau.

A couple of small changes to yours = a dragonfly:

The copy/paste code: y=tan((x^4/x^2-1)/(y^4/y^2-1))/x

Hi Bobby,

That one's amazing - particularly the feathering!

And Save works too...thanks, MathsIsFun.

I'll cheat and use Bobby's piccy (he's probably too modest for that), because I haven't come up with anything worth posting yet.

Hi Bobby & Sophie_A,

Bobby: Thanks for that explanation! Very clear, and a clever solution method. Once I got my head around the concept I found that doing the calculations of the two problems in my head was quite easy.

Yes, that's not too hard mentally, but I find it easier to deduct 12950 from 13090 to get 140, and dividing that by 35 to get 4.

Sophie_A: Ok - thanks. Got it. A few too many figures for my head to hold, though. As I see it, that method gets harder as the number of digits in the multiplier increases. eg, 1543? x 9155 = 141334890 is too hard for me to do in my head your way...but you may have some other shortcut to deal with that. Finding ? mentally by using Bobby's mod method is no harder than the other two shorter problems (apart from doing a few more digit sums).

Hi Bobby & Sophie_A,

Bobby: Sorry, but I'm not following what you're trying to do there. My only experience with mod is with the Excel "mod" function as it helped with my NOHOW and Telephone/YOB puzzle solutions - but that's all I understand about it.

Sophie_A: I tried your method on a problem I made up (386 x 85 = 32810) but it doesn't seem to work on that one. I'm probably doing something wrong, because I don't think I've understood your method.

With your original problem another easy option is to double the answer to 26180 and divide the result by 10 and then 7 to get 374.

If calculations have to be done totally mentally (ie, no looking at the problem during calculations), I'd probably prefer the single-digit division by 7, otherwise I think that division by the two-digit 35 (as per my second post) is easier (for me). There's not much in it.

Hi, Sophie_A.

My answer is

Hi MathsIsFun,

Like Bobby, I also was not offended by any of the posts here and I too was just trying to be funny. There was no thought at all of wounding anyone.

It is the way my golfing buddies and I talk, and have done so for many years. We're from different nationalities (Aussie, Indiginous, Dutch, English, Scottish, New Zealander) and very much enjoy each other's company, and a large slice of our enjoyment comes from joking around - including such as we've been doing here, and also in tearing one another down and reminding ourselves what rotten golfers we are. But we're also quick to praise.

The difference between that and public forum posts is that in our golfing group we know and understand one another well, and that pokes in the ribs are appreciated (we're one of the jolliest groups out there). And our comments remain private. 

I hadn't read the rules properly and I can see now that some of what I said breached them. They're wise rules for a forum like MIF. Causing offense, even in the slightest degree, is something I never want to be guilty of and so I've deleted my posts from this thread. I want my influence on the forum to be only positive.

I have a bit of a sideways-humour streak in me, but I'll try to keep a tighter rein on it.

I sincerely apologise for the part I played in the problem.

Hi Bobby,

While I was whiling away the hours in my time machine last night on that fruitless return journey with the plastic cheese, I had another go at solving this puzzle to see if I could find a solution strategy that was simple enough to do longhand. Nope - Excel was the only way forward for me.

I didn't mention this in the "Great big hint", but in the exercise there I used the Factors function that I gave a link to in an earlier post:

I don't know why something like this isn't included in Excel as standard equipment!

Hi Bobby,

Sorry, Bobby...I wanted to be more helpful than I've been so far, but I didn't know how to do that and at the same time not spoil the puzzle.

William Y. Sit, who I think eats cross-number puzzles for breakfast, says this about NOHOW:

That probably makes more sense to you than it does to me (it didn't help me one scrap), but in case it doesn't here's a MUCH bigger hint (I can't think of a smaller one that helps at all):

Hi,

For anyone wanting to use Excel to help them with this puzzle, here's a prime factorization function:

Excel doesn't have one, so it has to be added into Excel as a udf. Factors are output in a comma-delimited string in ascending order and contain repeat factors, if any. There's an option for the output to be in descending factor order, but that shouldn't be needed in this puzzle (it was specifically written into the function for another puzzle I posted earlier on that required that output order).

For all other formulas in my spreadsheet I used Excel's standard built-in functions.

Btw, I don't know that it's necessary to use a spreadsheet (or programming?) to help solve the puzzle, and quite possibly the puzzle's author intended a more logical and manual approach - but I can't find it and so resorted to using Excel.

But that was good too, because I like using Excel and things like this help me to get to know it better.

They're two excellent examples of ambiguity, soroban!

A bit like optical illusions that have two interpretations...after you see one the other may not be immediately apparent.