Chapter 11 - Counting Methods and Probability Theory - 11.1 The Fundamental Counting Principle - Exercise Set 11.1 - Page 693: 6

$234$

The number of ways in which a series of successive things can occur is found by multiplying the number of ways in which each thing can occur. ---------- 1. The first character, a letter, can be chosen in $26$ ways. 2. The second character, a digit, can be chosen in $9$ ways. Applying the Principle, the total number of labels is $26\times 9=234$