For a prime number greater than 5, what can the last digit be
? Explain your answer.
Why don't you list some of the primes, e.g.
7,11,13,17,19, 23, 29, 31 ....
notice it is not possible for any of these primes to be even
or have a 0, or 5.
That leaves 1,3, 7, or 9
Nice Question .I have clear
I know that the answer is 1,3,7 and 9 but I need explaination.
To determine the possible last digits of a prime number greater than 5, we can consider the property of divisibility by 2 and 5.
First, let's consider divisibility by 2. Any number that ends with an even digit (0, 2, 4, 6, or 8) is divisible by 2, except for the prime number 2 itself. Therefore, a prime number greater than 5 cannot end with an even digit (except for the number 2).
Next, let's consider divisibility by 5. Any number that ends with 0 or 5 is divisible by 5, except for the prime number 5 itself. Hence, a prime number greater than 5 cannot end with a 0 or 5 (except for the number 5).
Combining these two rules, we can conclude that for a prime number greater than 5, the last digit can only be 1, 3, 7, or 9. These are the only possible last digits for prime numbers greater than 5.
To determine whether a specific number is prime, you can use various methods such as primality tests, including trial division or probabilistic tests like the Miller-Rabin primality test.