The first digit can be any one of the numbers 2-9 That a total of 8 numbers.
The next 6 digits can be any permutation of 6  from the numbers  0 to 9.
(10 numbers)
nPr  =  n! / r!
so here we have  10P6  = 10! / 6!  =  10*9*8*7  =  5040
So final answer  is 8 * 5040 = 40,320