`` How did the '' '' _ + _ + _ = 30 using 1 , 3 , 5 , 7 , 9 , 11 , 13 and 15 '' '' riddle become so popular ? ''
Mathematical Puzzles : What is -LRB- -RRB- + -LRB- -RRB- + -LRB- -RRB- = 30 using 1,3,5,7,9,11,13,15 ?