Divisibility Rules for different divisors

For Divisor = 1

There is no specific condition. Every number is divisible by 1.

For Divisor = 2

If the last digit of the number is even, then that number is divisible by 2. For example, 0, 2, 4, 6, 8.

For Divisor = 3

• The sum of the digits is divisible by 3, then that number is also divisible by 3.
• Subtract the quantity of the digits 2, 5 & 8 from the quantity of the digits 1, 4, & 7. If this difference is divisible by 3, then that number is also divisible by 3. For Example, 16,499,205,854,376 has four of the digits 1, 4 and 7 and four of the digits 2, 5 and 8; since 4 − 4 = 0 is a multiple of 3, the number 16,499,205,854,376 is divisible by 3.
• Subtracting the last digit of the number twice from the rest of the number. If this difference is divisible by 3, then that number is also divisible by 3. _ For Example, 405: 40 − 5 × 2 = 40 − 10 = 30 = 3 × 10._

For Divisor = 4

• The last two digits form a number and that number is divisible by 4.
• If the tens digit is even, the ones digit must be 0, 4, or 8.
• If the tens digit is odd, the ones digit must be 2 or 6.
• The sum of the ones digit and double the tens digit is divisible by 4.