Introduction:
To find the number of four-digit numbers that are divisible by 2, we need to understand the concept of divisibility and the properties of even numbers. Divisibility refers to the ability of one number to be divided by another without leaving a remainder. Even numbers are divisible by 2, meaning they can be divided by 2 without any remainder.

Properties of Even Numbers:
1. Even numbers always end with either 0, 2, 4, 6, or 8.
2. The last digit of an even number is always divisible by 2.

Methodology:
To count the number of four-digit numbers divisible by 2, we need to consider the possible values for each digit.

Thousands Digit:
The thousands digit of a four-digit number can be any digit from 1 to 9 (excluding 0 since it would make the number a three-digit number). Therefore, there are 9 possible choices for the thousands digit.

Hundreds Digit:
The hundreds digit can be any digit from 0 to 9 since there are no restrictions on its value. Therefore, there are 10 possible choices for the hundreds digit.

Tens Digit:
The tens digit can also be any digit from 0 to 9. Therefore, there are 10 possible choices for the tens digit.

Units Digit:
The units digit must be an even number (0, 2, 4, 6, or 8) to ensure the number is divisible by 2. Therefore, there are 5 possible choices for the units digit.

Total Number of Four-Digit Numbers Divisible by 2:
To find the total number of four-digit numbers divisible by 2, we multiply the number of choices for each digit: 9 (thousands digit) x 10 (hundreds digit) x 10 (tens digit) x 5 (units digit) = 4,500.

Therefore, there are 4,500 four-digit numbers that are divisible by 2.