Question 1072909
a){{{N=9*9*9*9=6561}}}
b) {{{N=9*8*7*6=3024}}}
c) Look at numbers starting in 6,
{{{N=9*9*9}}}
Same number for numbers starting in 7,8, and 9.
So there are 4 sets of 9*9*9.
{{{N[tot]=4*9*9*9}}}
{{{N[tot]=2916}}}