California Assessment of Student Performance and Progress (CAASPP) Math Practice Exam

What is the largest three-digit prime number?

1. 991

2. 997

3. 999

4. 1000

The correct answer is: 997

The largest three-digit prime number is 997. A prime number is defined as a number greater than 1 that has no positive divisors other than 1 and itself. To determine if 997 is a prime number, you check for divisibility by prime numbers that are less than its square root (which is approximately 31.56). This includes 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, and 31. - 997 is not even, so it is not divisible by 2. - The sum of the digits of 997 is 25, which is not divisible by 3. - It does not end in 0 or 5, so it is not divisible by 5. - Upon checking divisibility by the other primes up to 31, none divide evenly into 997. Since 997 has no divisors other than 1 and itself, it is confirmed as a prime number. Furthermore, 991 is also a prime number, but it is smaller than 997. The numbers 999 and 1000 are both composite since 999 can be divided by 3 and 1000 is divisible