Divisibility Rules

Question 1

Number divisible by 0

Answer 1

No number is divisible by 0

Question 2

Number divisible by 1

Answer 2

All numbers are divisible by 1

Question 3

Number divisible by 2

Answer 3

If units digit is even (ones digit is 0,2,4,6, or 8)

ex. 30, 42, 54, 69376, 7,943,258

Question 4

Number divisible by 3

Answer 4

Sum of all digits is divisible by 3

ex. 472,071

Question 5

Number divisible by 4

Answer 5

Last 2 digits are divisible by 4

ex. 244, *100 too!

Question 6

Number divisible by 5

Answer 6

Units digit is 0 or 5

ex. 55, 70

Question 7

Number divisible by 6

Answer 7

Even number whose digits sum to a multiple of 3 (i.e. is divisible by 2 and 3)
ex. 18, 24, 144

Question 8

Number divisible by 7

Answer 8

Do it out - prime # so tested infrequently

Question 9

Number divisible by 8

Answer 9

Even number whose last 3 digits are divisible by 8

• All multiples of 1,000 are divisible by 8 (125 * 8 = 1000)
  ex. 1160, 872

Question 10

Number divisible by 9

Answer 10

Sum of all digits is divisible by 9

ex. 479,655

Question 11

Number divisible by 10

Answer 11

units digit is a 0

10, 80, 900, 10,000, 54,000

Question 12

Number divisible by 11

Answer 12

Alternate subtracting numbers from previous digit then sum those totals, if that sum is divisible by 11 then so is the orig number
2,915, 253

Question 13

Number divisible by 12

Answer 13

If the number is divisible by 3 & 4