The Rules for DivisibilityFocus 3: 6.NS.2

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"Divisible By" means "when you divide one number by another the result is a whole number“

(no remainders!)A number is divisible by……

2 if…The last digit is even (0,2,4,6,8)

128 Yes129 No

5 if…The last digit is 0 or 5

175 Yes809 No

10 if…The number ends in 0

220 Yes221 No

3 if…The sum of the digits is divisible by 3

381 (3+8+1=12, and 12÷3 = 4) Yes217 (2+1+7=10, and 10÷3 = 3 1/3) No

9 if…The sum of the digits is divisible by 9

1,629 (1+6+2+9=18, then, 1+8=9) Yes 2,013 (2+0+1+3=6) No

6 if…The number is divisible by both 2 and 3

114 (it is even, and 1+1+4=6 and 6÷3 = 2) Yes 308 (it is even, but 3+0+8=11 and 11÷3 = 3 2/3) No

4 if…The last 2 digits are divisible by 4

1312 (12÷4=3) Yes7019 (19÷4=4.75) NO

8 if…The last three digits are divisible by 8

109816 (816÷8=102) Yes 216302 (302÷8=37 3/4) No

There’s more! Not only are there divisibility tests for larger numbers, but there are

more tests for the numbers we have shown.

Factors Can Be Useful!! (Factors are the numbers you multiply to get another number.)

When a number is divisible by another number ... …then it is also divisible by each of the factors of that

number.

Example: If a number is divisible by 6, it is also divisible by 2 and 3 Example: If a number is divisible by 12, it is also divisible by 2, 3, 4 and 6