Question 281887
The 1st digit can be 1-9 or 9 possible numbers
The 2nd digit can be 1,3,5,or 9 or 4 possible numbers
The 3rd digit can be 0,2,4,or 8 or 4 possible numbers
The remaining digits can be 0-9 or 10 possible numbers
There are {{{9*4*4*10*10*10*10 }}} = 1,440,000 7-digit phone numbers