The probability that a randomly entered number is valid will be 0.00000003
Explanation
From 0 to 9, there are total 10 digits and the credit card number should be of 16 digits.
So, the total possible 16 digit credit card numbers [tex]=10^1^6[/tex]
Now, the valid numbers are only 300 millions [tex]i.e[/tex] [tex]3*10^8[/tex]
Thus, the probability that a randomly entered number is valid [tex]= \frac{3*10^8}{10^1^6}= 3*10^-^8 = 0.00000003[/tex]
