Which of the following is a correct divisibility rule for 2?

• A. The number is even
• B. The sum of digits is even
• C. The last digit is 5
• D. The number ends with 0

Answer: (A)

Divisibility by 2 is all about evenness: a number is divisible by 2 exactly when it is even, which means its last digit is even (0, 2, 4, 6, or 8). That’s why stating that the number is even is the correct rule—it covers every multiple of 2. Saying it ends with 0 is too narrow, since many numbers ending with 2, 4, 6, or 8 are also divisible by 2. The other ideas—the sum of digits being even or the last digit being 5—do not reliably indicate divisibility by 2.