Divisibility Rules

Question 1

How can you tell if an integer is divisible by 4?

Answer 1

The integer is divisible by 2 twice
-OR-
The last two digits are divisible by 4

Question 2

How can you tell if an integer is divisible by 6?

Answer 2

Integer is divisible by both 2 and 3

Question 3

How can you tell if an integer is divisible by 8?

Answer 3

Integer is divisible by 2 three times
-OR-
Last three digits are divisible by 8

Question 4

How can you tell if an integer is divisible by 9?

Answer 4

Sum of the integer’s digits is divisible by 9

Question 5

If integers a and b are both multiples of some integer k>1 (divisible by k), then their sum and difference

Answer 5

Will also be a multiple of k (divisible by k)

Question 6

If out of integers a and b one is a multiple of some integer k>1 and another is not, then their sum and difference

Answer 6

Will NOT be a multiple of k (divisible by k)

Question 7

If integers a and b both are NOT multiples of some integer k>1 (divisible by k), then their sum and difference

Answer 7

May or may not be a multiple of k (divisible by k)