Question

You have been assigned a 9 digit identification number.

Answer 1

Answer:

1,000,000,000 identification numbers are possible.

Step-by-step explanation:

We are assigned a 9 digit identification number.

Each digit is a number from 0 to 9. So, each digit has 10 different choices.

Using the Fundamental Counting Principle (is better than the tree diagram) because it's simpler. To illustrate this, we can attempt to draw a tree diagram.

The first column will be the digits 0 to 9.

Then for each of those digits, we need another 0 to 9.

As you can imagine, the amount of numbers grow exponentially, so using the Fundamental Counting Principle is simpler.

And since we have a 9 digit identification number, with each digit having 10 choices, the total number of identification numbers possible are:

$10\times 10\times 10 \times 10\times 10 \times 10 \times 10 \times 10 \time 10\times 10=10^9=100000000$

So, 1,000,000,000 identification numbers are possible.