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An Indian board commuinty questioned their students. No body answered but one of them.

The Question is simple: _+_+_=30

Numbers to be used:" 1, 3, 5, 7, 9, 11, 13, 15 " only (Odd numbers upto 15)

You can use same number  twice & can't put '0' anywhere in blanks.

Anyone out there to help?

Guest Apr 22, 2015

Best Answer 

 #9
avatar+520 
+10

It would be interesting to know exactly what the examiners had in mind. A lot hinges on what is meant by "using the numbers".

 

if we can use mod, here is one of infinite possibilities:

1357911 mod 13 + 111315 mod 13 + 13571 mod 13 = 30

 

    😡   😡   😡   😡   😡

Badinage  Apr 26, 2015
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10+0 Answers

 #1
avatar+90996 
+10

If you add 3 odd numbers the answer cannot be even.  Therefore they cannot add up to 30

Melody  Apr 22, 2015
 #2
avatar+520 
+8

Q: The Question is simple: _ + _ + _ = 30

 

A: 1(5) + 11(5) + 13(5) = 30(5)

 

♚   ♚   ♚   ♚   ♚   ♚ 

Badinage  Apr 22, 2015
 #3
avatar+26326 
+5

Nice try Badinage, but the question specifies odd numbers and 115 and 135 are even numbers!

.

Alan  Apr 22, 2015
 #4
avatar+520 
+5

The comment "(Odd numbers upto 15)" looks like the poster's interpretation designed to mislead, rather than part of the problem specification.  That's what I'm claiming!! 

Badinage  Apr 22, 2015
 #5
avatar+26326 
+5

But the number 15 is specified and there is no 155.

I like your lateral thinking though!  Try it with numbers to the base 7 (make sure the they are all odd).

.

Alan  Apr 22, 2015
 #6
avatar+520 
+5

There is significant ambiguity here (admittedly, that's what often makes math puzzles interesting!).

"Numbers to be used: ..." could be interpreted as ALL of these (sequences of digits) must be used at least once,

but then adding

"only" carries an implication that the solution is exclusive to those within that given sequence, and not that they all necessarily be utilised.

Also, it is not clear if the solution can include functions such as logn or power^(1/n)

 

So, possibly there is a whole raft of solutions, limited only by ones imagination.

   

Badinage  Apr 22, 2015
 #7
avatar+90996 
+5

Hi Alan and Badinage  

 

So Badinage, if there is a 'whole raft of solutions' are you going to give us one of them that Alan won't poke holes in ?  LOL

Melody  Apr 23, 2015
 #8
avatar+1068 
+5

The Question is simple: _+_+_=30

 

                 5 + 52 + ln1 = 30

civonamzuk  Apr 24, 2015
 #9
avatar+520 
+10
Best Answer

It would be interesting to know exactly what the examiners had in mind. A lot hinges on what is meant by "using the numbers".

 

if we can use mod, here is one of infinite possibilities:

1357911 mod 13 + 111315 mod 13 + 13571 mod 13 = 30

 

    😡   😡   😡   😡   😡

Badinage  Apr 26, 2015
 #10
avatar+90996 
0

 

Thanks Badinage :))

 

$${\mathtt{1\,357\,911}} \,{mod}\, {\mathtt{13}}{\mathtt{\,\small\textbf+\,}}{\mathtt{111\,315}} \,{mod}\, {\mathtt{13}}{\mathtt{\,\small\textbf+\,}}{\mathtt{13\,571}} \,{mod}\, {\mathtt{13}} = {\mathtt{30}}$$

 

BUT only odd numbers up to 15 were supposed to be used  

Melody  Apr 26, 2015

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