Question

In the early 1970's, Canada Post started using six-character postal coads. Each postal code uses three letters and three digits in an alternating pattern. How many different Canadian postal codes are possible

Answer 1

For the three letters, you can have 26^3 different zip codes
For the three digitd, you can have 10^3 different zip codes

Answer 2

For both you have
\[
26^3 10^3 =17576000
\]