Divisbility Rules

Question 0

By 3

Answer 0

If sum of digits is divisible by 3

Question 1

By 2

Answer 1

If even

Question 2

By 4

Answer 2

If last two digits is a number divisible by 4

Question 3

By 5

Answer 3

If ends in 5 or 0

Question 4

By 7

Answer 4

If difference between unites digit times 2 and rest of number is multiple of 7. Ex: 147 is divisible by 7: 14-(7x2)=0, which is divisible by 7

Question 5

By 8

Answer 5

If last three digits is a number divisible by 8

Question 6

By 9

Answer 6

If sum of digits is divisible by 9

Question 7

By 11

Answer 7

If difference between sum of odd-place digits (from left) and sum of even- place digits is divisible by 11. Ex: 5,181 is divisible by 11: (5+8)-(1+1)=11. OR: in a 3 digit number, if tens digits = sum of units and hundreds digits. Ex: 341 yes: (3+1)=4. CANNOT RULE OUT DIVISIBLITY

Question 8

Using rules with factorization

Answer 8

Test rules using factors to test if divisible by their multiple (only if factors don’t have factors in common) Ex: to be divisible by 44, number must be divisible by 4 and 11.