Divisibility by 2. A number is divisible by 2, if its last digit is 0 or is divisible by 2. Numbers, which are divisible by 2 are called even numbers. Otherwise, numbers are called odd numbers.

Divisibility by 4. A number is divisible by 4, if its two last digits are zeros or they make a two-digit number, which is divisible by 4.

Divisibility by 8. A number is divisible by 8, if its three last digits are zeros or they make a three-digit number, which is divisible by 8.

Divisibility by 3 and by 9. A number is divisible by 3, if a sum of its digits is divisible by 3. A number is divisible by 9, if a sum of its digits is divisible by 9.

Divisibility by 6. A number is divisible by 6, if it is divisible by 2 and by 3.

Divisibility by 5.v A number is divisible by 5, if its last digit is 0 or 5.

Divisibility by 25. A number is divisible by 25, if its two last digits are zeros or they make a number,
which is divisible by 25.

Divisibility by 10. A number is divisible by 10, if its last digit is 0.

Divisibility by 100. A number is divisible by 100, if its two last digits are zeros.

Divisibility by 1000. A number is divisible by 1000, if its three last digits are zeros.

Divisibility by 11. A number is divisible by 11 if and only if a sum of its digits, located on even places is equal to a sum of its digits, located on odd places, OR these sums are differed by a number, which is divisible by 11.

There are criteria of divisibility for some other numbers, but these criteria are more difficult and not considered in a secondary school program.