All numbers that end in five are divisible by five. Therefore all numbers that end with five and are greater than five are composite numbers. the prime numbers between 2 and 100 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59,
61, 67, 71, 73, 79, 83, 89 and 97 so 79 is prime :)))