Answer:
1/4 or 0.25
Step-by-step explanation:
The total possibilities of any 7 digit number using 0-9 is : 
9×10×10×10×10×10×10=9000000
To work out the total possibilities in this question : 
We look at the conditions : 
The first digit can only be 5 numbers : 
1 , 3 , 5 , 7 , 9 
Now we subtract 5 from 9 : 
9-5 = 4 
Since no repeats for 2 , 3 , 4, 5, 6: 
9 , 8 , 7 , 6 , 5,   
5 possibilities for the last digit : 
Total possibilities for this code : 
4 × 9 × 8 × 7 × 6 × 5 × 5 = 302400
If it begins with 5 that is only 1 possibility for the first digit 
1 × 9 × 8 × 7 × 6 × 5 × 5 = 75600 
Now we make a fraction : 
75600÷302400 
Dividing top and bottom by 75600 gives you 1/4 or 0.25 
Hope this helped and have a good day