Simon picks a 4-digit number at random.
The first digit is not a zero.
The 4-digit number is a multiple of 5.
How many different 4-digit numbers could Simon pick?
Answer:
There are 9 possibilities for the first digit, 10 for the second and third and 2 for the last.
By the Product Rule for Counting:
Total number of ways = 9 x 10 x 10 x 2 = 1800.