A natural number is divisible by 5 if and only if the last digit is 0 or 5.

730 is divisible by 5 since the last digit (0) is 0 or 5.

733 is NOT divisible by 5 since the last digit (3) is (NOT 0 or 5.

716 123 456 789 098 765 432 105 is divisible by 5 since the last digit (5) is 0 or 5.

717 123 456 789 098 765 432 109 is NOT divisible by 5 since the last digit (9) is NOT 0 or 5.