Answer:
10000
Step-by-step explanation:
From 0 to 9 is 10 possibilities for each digit. I like to picture it like this:
There are four spots, one for each digit:
__ __ __ __
Each has ten possibilities:
_10_ _10_ _10_ _10_
Because these are independent events, we multiply them:
_10_ x _10_x _10_x _10_
The answer is 10^4 or 10000!
