Arithmetic problem - brainbox required !

[dibbly_dobbler]

A brainy chum of mine at work gave me the following problem and I'm stumped !

a,b,c,d are integers. Using no number more than once per calculation and using only addition and subtraction you can get 1 to 40 inclusive. Solve for a,b,c,d

I've had a few goes and failed horribly - help !

[Rob.]

42.

HTH.

[Snake the Sniper]

Do you have to use a, b, c + d in all equations?

[AlpineWhite]

can an integer just be itself

say a=4, could you just say 4=4?

[dibbly_dobbler]

Snake the Sniper said:

Do you have to use a, b, c + d in all equations?

No - just as required.

For instance 7,9,10,14 got me from 1-17 inclusive bit then I got stuck...

[TWSTEEL]

Just a thought but as long as it's a whole number it's an integer and it can be a minus number, so sticking a negative integer in doubles its usefulness as when you subtract from a minus number you add to it.

[mybrainhurts]

I blame global warming...

[Shaw Tarse]

Rob. said:

42.

HTH.

the answer is 42!

[Austin.J]

mybrainhurts said:

I blame global warming...

Canada is the place to blame...

[CrashTD]

TWSTEEL said:

Just a thought but as long as it's a whole number it's an integer and it can be a minus number, so sticking a negative integer in doubles its usefulness as when you subtract from a minus number you add to it.

but you can use addition and subtraction

[mccarn]

I've been at the pub tonight so its not making much sense

Edited by mccarn on Tuesday 2nd December 22:09

[Titan Simba]

Shaw Tarse said:

Rob. said:

42.

HTH.

the answer is 42!

The answer is ALWAYS 42!

[glencooley]

Its a fibonacci sequence

[CivicMan]

I'm getting -42.

[AlpineWhite]

27, 9, 3, 1. I think.

[glencooley]

i thought

1,5,13,21

but yours is better ^^^^

[TWSTEEL]

CrashTD said:

TWSTEEL said:

Just a thought but as long as it's a whole number it's an integer and it can be a minus number, so sticking a negative integer in doubles its usefulness as when you subtract from a minus number you add to it.

but you can use addition and subtraction

Of course - what a plonker I am!!!!!

OK so if you start subtracting your larger intergers from your smaller ones you create "new" integers to use in your............

[TVR MAN]

I'm still checking this but my guess is 1,3,5,7.

It's fine up to 23 so far.

[AlpineWhite]

Using only addition and subtraction! I'm not sure how you're going to get past 16 fella.

[glencooley]

TVR MAN said:

I'm still checking this but my guess is 1,3,5,7.

It's fine up to 23 so far.

You can only use addition and subtraction......added all together they dont make 23???