Question

_+_+_=30
(1,3,5,7,9,11,13,15)

Answer 1

not possible as there are odd numbers to be filled and number of blanks are odd too
and odd times odd is odd but we know that 30 is an even number so it is not possible ..however some uses 3! tricks but i think thats wrong too coz its numerical value is 6 which is not given in the given question

Answer 2

This is not solvable in the normal arithmetic method of addition of the numbers given.  We have to have three even numbers or  one even number and two odd numbers to get the result as an even number.  But we dont have any odd number in the given set of numbers in the parentheses.

We need to use an operator like  a factorial or some other one, which yields an even number taking an odd number as the input.  Logarithm is an operator or a function which also can give an even number.

It is left to imaginative skill and knowledge of the person to answer this question.

     3!   +  11  + 13    = 30
     15 + 15 + Log 1  = 30          ,  as Log 1 = 0  to any base.
$15+13+Log_3\ 9 = 30,\ as\ Log_3\ 9=2$
      3*7 + 9 + Log 1  = 30
     15  +  13  + 3!/3  = 30
     (1+3)! + 1 +  5    = 30
     3³  +  3!/3 +  1    = 30
     9 + 1 + 5!/3!       = 30
     15³/5³  + 1 + 3! / 3 = 30