Transcript Divisibility Rules for 6th grade Math

These rules let you test if one
number can be evenly divided
by another, without having to
do too much calculation!
Divisibility rules can be used:
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to find out if a number is prime or
composite
to help find factors of a number
to find GCF and LCM when dealing
with fractions
A number is divisible by 2, if
the ones digit is divisible by 2
For example:
746 is divisible by 2…
because 6 is divisible by 2
6÷2=3
(hint: any even # is divisible by 2!)
A number is divisible by 3, if the
sum of the digits is divisible by 3
For example:
12,321 is divisible by 3 …
because 1+2+3+2+1=9
9 is divisible by 3
9÷3=3
A number is divisible by 4, if the
number formed by the last two
digits is divisible by 4
For example:
824 is divisible by 4…
because 24 is divisible by 4
24÷4=6
A number is divisible by 5, if the
number ends in a 0 or 5
For example:
120 and 325 are both divisible by 5
120 ends in 0
325 ends in 5
A number is divisible by 6, if the
number is divisible by 2 and 3
For example:
36 is divisible by 2 since 6 is even
36 is divisible by 3 since 3+6=9
and 9 is divisible by 3
So, 36 is divisible by 6!
A number is divisible by 7, if you can
take the last digit, double it and
subtract it from the remaining number
and the answer is divisible by 7
For example:
203 is divisible by 7…
because 3 doubled is 6, and 20-6=14
14 is divisible by 7
14÷7=2
A number is divisible by 8, if the
last three digits are divisible by 8
For example:
1280 is divisible by 8…
because 280 is divisible by 8
280÷8=34 so, 1280÷8=160
A number is divisible by 9, if the
sum of the digits is divisible by 9
For example:
7056 is divisible by 9…
because 7+0+5+6=18
and 18 is divisible by 9
18÷9=2
A number is divisible by 10, if the
last digit is a zero
For example:
100, 240, 3750, 48,720 are all
divisible by 10
If you memorize the
divisibility rules,
math will become
easier!
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2 if the ones digit is divisible by 2
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3 if the sum of the digits is divisible by 3
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4 if the # formed by the last two digits is
divisible by 4
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5 if the last digit is a 0 or 5
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6 if the # is divisible by 2 and 3
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9 if the sum of the digits is divisible by 9
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10 if the last digit is a 0
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