Question

Show 15^n cannot end with 0, 2, 4, 6 or 8 for any natural number n

Answer 1

Answer:

The prime factorization of 15 is 3×5. By observation, (3×5) ^n is divisible by 5 but not by 2. Hence, 15 ^n is not divisible by 10. Hence, 15 ^n does not end with digit 0 for any natural number n.