`` How did the '' '' _ + _ + _ = 30 using 1 , 3 , 5 , 7 , 9 , 11 , 13 and 15 '' '' riddle become so popular ? ''
How many 6 digit number can be formed by using the digits 0,1,2,3,4,5,6,7,8 . If every number is to start with 30 with no digit repeated ?