A Fistful of Brain Teasers
Posted by: Don Atkinson on 13 November 2017
A Fistful of Brain Teasers
For those who are either non-British, or under the age of 65………. The UK used to have a brilliant system of currency referred to as “Pounds, Shillings and Pence”. Simplified to £ ״ s ״ d. No! Don’t ask me why the “Pence” symbol is a “d”, just learn it and remember it !
A £ comprised 20 Shillings and a Shilling comprised 12 Pence. Thus a £ comprised 240 Pence. I reckon that both Microsoft and Apple would have difficulty with these numbers in their spreadsheets, more so if we included Guineas, Crowns, Half-Crowns and Florins. However, I digress..............
The purpose of the explanation is to assist with the first two or three teasers that follow. So just to ensure a reasonable comprehension has been grasped…. ….. if each of three children has £3 − 7s − 9d, then collectively they have £10 − 3s − 3d Got the idea ? Good ! Just try 5 children, two each with £4 − 15s − 8d and three each with £3 − 3s − 4d. How much do they have between them ? (this isn’t the first brain teaser, just the basic introduction with some “homework”, the Teasers follow)
Don Atkinson posted:
Hi Eoink,
It's not meant to be pedantic, and I hope it isn't.
It doesn't matter whether he's good for part of each and every day, or good for the first part of the month then rotten for the rest, or simply good and bad at random.
But 13.333 x 8 shillings doesn't = 16.667 x 10 shillings so can't be the correct answer.
I sometimes think, that as we get older we read these simple maths questions with a cynical, semi-political outlook. eg where's the catch ?; do the words have a hidden meaning ? and we challenge poorly-worded or slightly ambiguously worded questions.
This one was meant to be simple. How do you divide 30 such that "A" x 8 = "B" x 10.
The story-line is the "teaser" part. ie can you unravel the story......
Hope this helps
Sorry Don, I saw what I’d written and realised it sounded negative when I meant anything but, but when I went to edit it, I’d missed the 15 minute window. I’m really enjoying these, I don’t have enough time usually to do them first, so I don’t read down and see other people’s answers. On this one I’d done the “hard sums”, recognised the numbers as be8ng what I’d got and didn’t spot the swap, so was trying to think what was the possible tweak, rather than reading carefully.
i’m genuinely sorry I sounded negative, it was very sloppy writing on my part, apologies again.
Eoink posted:Don Atkinson posted:
Hi Eoink,
It's not meant to be pedantic, and I hope it isn't.
It doesn't matter whether he's good for part of each and every day, or good for the first part of the month then rotten for the rest, or simply good and bad at random.
But 13.333 x 8 shillings doesn't = 16.667 x 10 shillings so can't be the correct answer.
I sometimes think, that as we get older we read these simple maths questions with a cynical, semi-political outlook. eg where's the catch ?; do the words have a hidden meaning ? and we challenge poorly-worded or slightly ambiguously worded questions.
This one was meant to be simple. How do you divide 30 such that "A" x 8 = "B" x 10.
The story-line is the "teaser" part. ie can you unravel the story......
Hope this helps
Sorry Don, I saw what I’d written and realised it sounded negative when I meant anything but, but when I went to edit it, I’d missed the 15 minute window. I’m really enjoying these, I don’t have enough time usually to do them first, so I don’t read down and see other people’s answers. On this one I’d done the “hard sums”, recognised the numbers as be8ng what I’d got and didn’t spot the swap, so was trying to think what was the possible tweak, rather than reading carefully.
i’m genuinely sorry I sounded negative, it was very sloppy writing on my part, apologies again.
Hi Eoink,
No need to apologise, it didn't sound negative to me, I've mis-typed a few questions in the past, or omitted a key feature, A few people have had to ask me to clarify things.
Main thing is to get the old grey matter going again and to enjoy a puzzle without any deadline or consequence............
steved posted:With fingers crossed for no carelessness this time, I get the answer as 3.429 minutes (or 60/17.5).
I think you can relax steve ! (24/7) 
Don Atkinson posted:steved posted:Agreed with Eoink. An interesting puzzle in that solving the equations "mathematically" quickly gets complicated, but the solution easily yields when the range of possible solutions is investigated.
That’s what I felt. It took a while to realise that the range is limited by “squares” less than 62.
Exactly, it's a very clever question. You look at it for a while trying to find a general solution, decide that brute force is the only practical way, sigh and get ready for a slog, then look at the 62 and realise it's a very manageable set, especially if like me you start at 7 to work down. 