Question

Serial numbers for a product are to be made using 2 letters followed by 4 digits. The letters are to be taken from the first 7 letters of the alphabet, with no repeats. The digits are taken from the 10 digits (0, 1, 2, ..., 9), with no repeats. How many serial numbers can be generated?

Answer 1

Explanation:

There are 7 choices for the first letter and 6 choices for the second letter. There are 10 choices for the first digit, 9 choices for the second digit, 8 choices for the third digit, and 7 choices for the fourth digit. Hence, there are 7*6*10*9*8*7 = 1,058,400 possible serial numbers.