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# Riddle watch

1. Just been given this riddle by my uncle and I can't seem to solve it!

I have X amount of money. If I had as many pounds as pence and many pence as pounds, I would have twice what I have. How much money do I have?

And no, the answer is not 'I have X amount..' :P
2. (Original post by Clubba)
Just been given this riddle by my uncle and I can't seem to solve it!

I have X amount of money. If I had as many pounds as pence and many pence as pounds, I would have twice what I have. How much money do I have?

And no, the answer is not 'I have X amount..' :P

Clue: It is less than £100 apparently

Let me try...

Let X=A pounds + B pence
convert into pence
X=100A+B
you have twice as many when you swap,
2X=Bpounds +A pence
convert into pence
2X=100B +A
equating the two

200A+2B=100B+A
199A=98B
(199/98)A=B
...
If X<100
Since X= 100A+B
100A+B<100
100A+(199/98)A<100
A<0.98
Well, not sure if this is the way to do it.
3. Zero.
4. (Original post by whyeverynameisus)
Let me try...

Let X=A pounds + B pence
convert into pence
X=100A+B
you have twice as many when you swap,
2X=Bpounds +A pence
convert into pence
2X=100B +A
equating the two

200A+2B=100B+A
199A=98B
(199/98)A=B
...
If X<100
Since X= 100A+B
100A+B<100
100A+(199/98)A<100
A<0.98
Well, not sure if this is the way to do it.

Please tell me you did not just try to solve a riddle with what you learn in maths class

5. I'm pretty sure this is easy peasy logic!

Because we have unknown quantities the answer could, in heinseight, be anything.
The closest we can get to an answer would be to examine the boundaries of pennies and pounds

100p = £1
1p = well, 1p

The lowest amount we can have is 1p. So 1p and £1 is impossible, because they're both origins.
So £2 and 2p is double £1 and 1p which would satisfy the riddle.

Saying this there are alot of possible answers as you could more a less double anything up to 100. However this is evidently the origin and < £100.

Would love to know if I'm correct=p
6. (Original post by whyeverynameisus)
Let me try...

Let X=A pounds + B pence
convert into pence
X=100A+B
you have twice as many when you swap,
2X=Bpounds +A pence
convert into pence
2X=100B +A
equating the two

200A+2B=100B+A
199A=98B
(199/98)A=B
...
If X<100
Since X= 100A+B
100A+B<100*100.....here is where you blundered
100A+(199/98)A<100
A<0.98
Well, not sure if this is the way to do it.

Have another go
7. (Original post by Acidy)
I'm pretty sure this is easy peasy logic!

Because we have unknown quantities the answer could, in heinseight, be anything.
The closest we can get to an answer would be to examine the boundaries of pennies and pounds

100p = £1
1p = well, 1p

The lowest amount we can have is 1p. So 1p and £1 is impossible, because they're both origins.
So £2 and 2p is double £1 and 1p which would satisfy the riddle.

Saying this there are alot of possible answers as you could more a less double anything up to 100. However this is evidently the origin and < £100.

Would love to know if I'm correct=p
8. (Original post by whyeverynameisus)
Let me try...

Let X=A pounds + B pence
convert into pence
X=100A+B
you have twice as many when you swap,
2X=Bpounds +A pence
convert into pence
2X=100B +A
equating the two

200A+2B=100B+A
199A=98B
(199/98)A=B
...
If X<100
Since X= 100A+B
100A+B<100
100A+(199/98)A<100
A<0.98
Well, not sure if this is the way to do it.
I have to say... I can continue this and find two inequality, but is that what you want? the problem is that ,very likely, I can only find a range, instead of a exact answer.

I pretty sure that Math is a way to solve question, otherwise, why Math exists?
9. (Original post by Acidy)
I'm pretty sure this is easy peasy logic!

Because we have unknown quantities the answer could, in heinseight, be anything.
The closest we can get to an answer would be to examine the boundaries of pennies and pounds

100p = £1
1p = well, 1p

The lowest amount we can have is 1p. So 1p and £1 is impossible, because they're both origins.
So £2 and 2p is double £1 and 1p which would satisfy the riddle.

Saying this there are alot of possible answers as you could more a less double anything up to 100. However this is evidently the origin and < £100.

Would love to know if I'm correct=p
That's the bit that I am talking about, are inequalities the answers?
10. This was on that Dara O'Briains maths show on dave.
I remember working it out and then throwing the piece of paper in the bin :P
11. Is it meant to mean zero like someone suggested above? (zero is 2x0).

I think that's the only answer. I thought about it and figured out that the pence has to be 50 or more (because it has to add more than a pound... if it was less than 50 and less than 2xpounds it wouldn't be enough, and if it was less than 50 and =/> 2xpounds then the pounds are not enough to make the pence be doubled. AWFUL explanation sorry but hopefully it makes sense to someone!)

So then I started from 50 and went up, and 33.67 is the closest you can get.

So in short yes he must mean zero!

xxx
12. You have £99.99

Switching pounds and pence you have £199.98 which is exactly double.
13. Very similar question here http://uktv.co.uk/dave/homepage/sid/9132 in question 5.

Not sure yours is solvable, other than for 0.
14. Bear in mind both A and B have to be integers.

(Original post by whyeverynameisus)
I have to say... I can continue this and find two inequality, but is that what you want? the problem is that ,very likely, I can only find a range, instead of a exact answer.

I pretty sure that Math is a way to solve question, otherwise, why Math exists?
15. The answer is 98 pounds and 199 pence. Confusing.... but correct.

Sorry, posted two things separately which I meant to post together. Whoever did the simultaneous equations above did it correct but neglected to consider that A and B are integers. If you realise that then you're ok...
16. Ohh I thought I came to solve a riddle, not a ****ing maths question.
17. I got £99.99?

Spoiler:
Show
Same method as whyeverynameisus:
Let X=A pounds + B pence
convert into pence
X=100A+B (equation 1)
you have twice as many when you swap,
2X=Bpounds +A pence
convert into pence
2X=100B +A (equation 2)
equating the two

200A+2B=100B+A
199A=98B
(199/98)A=B
Then did the same for A: 199A = 98B so A = (98/199)B

used the fact that X < (100*100)p to say 100A + 199/98A < 100*100 A < (10,000/(100+199/98)) A < 98p
Did the same for B and got it as < 199p which is just the two numbers we had relating them anyway xD

Then just decided to substitute them into equations 1 and 2 using A = 98p and B = 199p
and you get X = 100*98 + 199 = 9999p = £99.99
so 2x should be £99.99 * 2 = £199.98
sub into equation 2 to check: 2X = 100*199 + 98 = 19998p = £199.98p

seems to work and the amount (£99.99) is juuuust under £100 but I've probably done something wrong :P
18. Thanks for your replies guys Il take £99.99 as the answer :P
19. (Original post by Ansolon)
The answer is 98 pounds and 199 pence. Confusing.... but correct.
knew someone would've got it by the time I typed it out

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