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Question

Can u find 14  with using the odd numbers  (1,3,5,7,9)but just only +& -

Notwen · Accepted Answer

Hello,

it seems to easy... :

14 = 7 + 7 = 9 + 5

Those are 2 answers with odd one-digit numbers. There are many more answers if you really meant odd numbers.

The_legend · Answer

nooo,u can only use (1,3,5,7,9)only once and u have to use all of these

Notwen · Answer

I you mean using those five numbers only once, in four operations to be chosen among (+,-), then it's easy to prove that there is no solution.

The_legend · Answer

yes..,there is a solution with these

Notwen · Answer

I will write the proof for you :

When you add or substract an even number of odd numbers, you obtain an even number.
When you add or substract an odd number of odd numbers, you obtain an odd number.

Five is an odd number, 1, 3, 5, 7 and 9 are 5 odd numbers, then adding or substracting those gives an odd number. No matter how you order the operations.

Conclusion : it can NOT give 14.

The_legendyes..,there is a solution with these

If you think I have, for the second time, misunderstood the statement of your problem, please be kind enough to express it more clearly. For example if you meant it in base 11 instead of 10, please state it clearly.
Or find an error in my proof if you can.

Anonymous · Answer

There is no mathematic error in Notwens proof.

But I think legend was meaning this...

9+5-3-7=4 and then there is left 1 and 4

Now we have "used" all these numbers only ones and found 14.

Have I found the solution?

Notwen · Answer

Hi,

this is funny

At least you have found a statement and a solution that could more or less fit The legend's demand !

With such vague statements, we can look for other solutions, for example :
9 - 5 + 3 + 7 = 14 and 14¹ = 14

Or in base eleven, we have 9 + 7 + 1 + 3 - 5 = 14 (because 14 is the way to write fifteen in base eleven)
In base fifteen : 9 + 7 + 5 - 3 + 1 = 14
Etc.

Or 19 - 3 - 7 + 5 = 14
Or 15 - 3 + 9 - 7 = 14

The more vague the statement, the more solutions you find... (Hum... does this sentence sound English ?)

Anonymous · Answer

Well, my younger brother came up with this solution and it seems the most suitable one.

9 + 7 + 5 + 3 - 1 = 9 + 14

Monox D. I-Fly · Answer

The_legend yes..,there is a solution with these

15 - 3 - 7 + 9 = 14

Is this the loophole you refer to, that the numbers aren't necessarily single digits?

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