The standard serial numbers for medical licence are 3 letters followed by 5 digits. How many different medical licenses are possible if letters and digits can be repeated?  Choose the correct choice.
A) 26 × × 3 × 5
B) 26³ × 10 000
C) 26³ x 100 000
D) 26 × 25 × 24 × 10 × 9 × 8 × 7
E) 26³ × 10 000 x 15
OFFICIAL SOLUTION:   (C) The formula for permutations of events is the product of the number of ways each event can occur. There are 26 letters and 10 digits. So there are 26 × 26 × 26 options for the three letters, and 10 × 10 × 10 × 10 x 10 for the five digits. The number of different Medical license is 26 × 26 × 26 × 10 × 10 × 10 × 10 x 10= 26³ × 100 000.   The correct answer is choice (26³ x 100 000).
<result>C</result>
The standard serial numbers for medical licence are 3 letters followed by 5 digits. How many different medical licenses are possible if letters and digits can be repeated?