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Divisibility Rules
“How do I know if I can divide
this number?”
What does “divisible” mean?
 If
a number has a remainder of “0”
when divided by another number,
then it is said to be divisible by that
number.
 Ex.
16 / 2 = 8
 Therefore, 16 is divisible by 8.
Is this number divisible by 2?
A
number that ends in 2, 4, 6, 8, or 0
is divisible by 2.
Is this number divisible by 3?
 If
the sum of the digits is divisible by
three, then so is the number.
 Ex. 24 => 2 + 4 = 6 , is 6/3…yes;
therefore, 24 is divisible by 3.
 Ex. 342=> 3 + 4 + 2 = 9 and 9/3;
therefore, 342 is divisible by 3.
Is this number divisible by 4?
 If
the last two digits are divisible by
4, then the whole number is divisible
by 4.
 Ex. 4324…the last two digits are 24
and 24/4 = 6; therefore, 4324 is
divisible by 4.
Is this number divisible by 5?
 If
the number ends in 5 or 0, then it
is divisible by 5. (If the ones digit is
5 or 0, then it is divisible by 5.)
 Ex. Are the following numbers
divisible by 5?
5
yes
 15 yes
 18no
-- 25 yes
-- 516 no
-- 348925415 yes
Is this number divisible by 6?
 If
the number is divisible by 2 and 3,
then it is divisible by 6.
 Ex. 216
 /2 (ends in 6) yes
 /3 (2+1+6=9) yes
 /6 ( /2 and /3) YES
Is this number divisible by 7?
 The
rule is too way too LONG to
remember…therefore, divide it out
and see is you get a remainder.
Is this number divisible by 8?
 If
the number formed by the last 3
digits is divisible by 8, then the whole
number is divisible by 8.
 Ex. 6320 … 320/8 = 40; therefore,
6320 is divisible by 8.
Is this number divisible by 9?
 If
the sum of the digits is 9, then the
number is divisible by 9.
 Ex. 5130
5 + 1 + 3+ 0 = 9;
therefore, 5130 is divisible by 9.
Is this number divisible by 10?
 If
the one’s digit is 0, then the
number is divisible by 10.
 100
yes
 150
yes
 80000 yes
 141352
NO
 687200
yes
 741812.9 NO