How many seven-digit numbers are there when 0 , 7 , and 2 cannot be the leading number?

 9,000,000
-2,000,000 (1,000,000 for each of the numbers taken out except 0, a number    7,000,000                   can't start with 0 unless it is 0 or a decimal.)

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.