discussion Money puzzle

[Gern]

My brother sent this to me today - the sadistic b****r!

Suppose you have £50 for your birthday and want to spend it. You write down two columns. One showing how much you spend and one showing how much you have left. Like so:

Spent Money left

Now start filling in the amounts:

Spent Money left

£20 £30
£15 £15
£9 £6
£6 £0

All OK so far?

Now add up the totals for each column .....

What's going on? And why can't I do this lots of times and end up fabulously rich?:upside:

 

[Gern]

Sorry folks, but the software has changed the spacing. You can still see what's happening though.

 

[boatman]

Sorry folks, but the software has changed the spacing. You can still see what's happening though.

WELL Dave all ok as far as i can see with what you started off with the 50 quid an then whats spent an whats left it seems to me you are a quid in pocket ? yea its weird counting up whats left eh but maths was never my strong point but i see what you mean on whats left
chrisb

 

[Valeron]

You're brother is a pain. I've just some time on this and don't get where th3 extra £1 came from.

 

[Jim R]

Thanks Dave. I'm off down the cash machine and gonna draw out my savings. I'll be rich by lunchtime.
Yippee! :thumb2: :smiling: :rolling:

 

[Tim Marlow]

Don’t know Dave, but if you spend it in increments of 10, 20, and 20 you will end up even better off….because that leaves 40, 20, and 0……and if you spend it one pound at a time you will end up as rich as creosote….

 

[Valeron]

My daughter who is good at maths says

"They've just used numbers that make it close to £50 to make you feel they should be the same but they shouldn't be. Money left it's cumulative"

 

[Guest]

if you spend it one pound at a time you will end up as rich as creosote….

Well, with £1225 anyway

 

[Tim Marlow]

Well, with £1225 anyway :smiling3:

Somehow I just knew you’d have to add that up Jakko :thumb2:

 

[stillp]

If only you knew a maths teacher who could explain it to you Dave... :tongue-out:
Pete

 

[Guest]

Somehow I just knew you’d have to add that up Jakko :thumb2:

View attachment 471267

 

[Tim Marlow]

:smiling3:

Funnily enough, that’s just how I visualised it…..

 

[KarlW]

I used (49/2)*(1+49)=1225
Like I was taught at school...........
sum of consecutive numbers=(n/2)*(first number+last number)
n=number of numbers

 

[Gern]

I used (49/2)*(1+49)=1225
Like I was taught at school...........
sum of consecutive numbers=(n/2)*(first number+last number)
n=number of numbers

That's what I was taught - just over 50 years ago - and not used it since!

 

[Tim Marlow]

That's what I was taught - just over 50 years ago - and not used it since!

Remember the mathematical society toast Dave……”Pure maths, long may it be of no use to anyone!”

 

[Guest]

I used (49/2)*(1+49)=1225
Like I was taught at school...........

I can’t recall ever being taught anything like that … Mathematics was never my strong suit largely because of it being too abstract for it to come easily to me — it would have been nice had they taught us practical solutions like that.

FWIW, the other way I would have solved it would have been:

% python
Python 3.9.6 (default, Oct 18 2022, 12:41:40) 
[Clang 14.0.0 (clang-1400.0.29.202)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> total = 0
>>> for n in range(1,50):
...     total += n
... 
>>> print(total)
1225

 

[Gern]

If only you knew a maths teacher who could explain it to you Dave... :tongue-out:
Pete

Yeah. But just about all I got was geometry, trig and calculus - of absolutely no use in the real world! I could have done with some statistics, which seems to be very trendy in secondary education nowadays, but it was seen as mere arithmetic back then so wasn't on the syllabus I was taught.

 

[boatman]

WELL i could never do logsarithims which to me seemed a total waste of time an still cant
chrisb

 

[Guest]

I could have done with some statistics, which seems to be very trendy in secondary education nowadays, but it was seen as mere arithmetic back then so wasn't on the syllabus I was taught.

Sounds a bit like, but even worse than, how it was when I went to Dutch secondary school in the 80s/early 90s. We had a choice of what was known as Maths A and Maths B. Maths A was intended for those who took subjects like Economics, Maths B for those who took things like Physics and Chemistry. The former taught statistics and stuff, the latter the more “hard” mathematics. As a result, everything I know about statistics, I picked up as a result of playing games (non-computer) because I was never even taught anything as simple as the chance of a coin landing on one side vs. the other.

 

[Tim Marlow]

Sounds a bit like, but even worse than, how it was when I went to Dutch secondary school in the 80s/early 90s. We had a choice of what was known as Maths A and Maths B. Maths A was intended for those who took subjects like Economics, Maths B for those who took things like Physics and Chemistry. The former taught statistics and stuff, the latter the more “hard” mathematics. As a result, everything I know about statistics, I picked up as a result of playing games (non-computer) because I was never even taught anything as simple as the chance of a coin landing on one side vs. the other.

Sounds like the A level options I had in the late seventies. Maths and stats for those doing biology, and Applied maths for those doing Chemistry and Physics…..
I studied Biology and Chemistry, so did the stats set and never used any of it……those doing Applied maths, chemistry and physics loved it….apparently it was like doing two and a half A levels instead of three…..