Answer:
729
Step-by-step explanation:
Including 3, there are 10 digits, from 0 to 9.
If you exclude 3, then there are 9 digits.
Each code will have a first digit, a second digit, and a third digit.
Each of those three digits can be chosen from 9 different digits.
We use the counting principle, and we multiply the number of possible digits for each position in the code.
number of possible first digits * number of possible second digits * number of possible third digits =
= 9 * 9 * 9 = 729
Answer: 729
