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VC DEPARTMENT OF MATHEMATICS
REVISED FALL 2005
DIVISIBILITY RULES AND PRIME FACTORIZATION
2 (Prime)
A number is divisible by 2 if its
last
digit is 0, 2, 4, 6, or 8. Any even number is divisible by 2.
3 (Prime)
Add
all
of the digits composing the number. If the sum of the digits is divisible by 3, then so
is the original number. Example
: If the number is 564, add 5 + 6 + 4 = 15
. The sum of the
digits (15
) is divisible by 3, so 564 is also divisible by 3.
4 (Composite)
A number is divisible by 4 if the number formed by its
last two
digits is divisible by 4, or if
the number ends in 00. Examples
: The number 5748 is divisible by 4 because the number
formed by its last two digits (48
) is divisible by 4. The number 300 is divisible by 4 because it
ends in 00
.
5 (Prime)
A number is divisible by 5 if its
last
digit is 0 or 5.
6 (Composite)
A number is divisible by 6 if it is divisible by
both
2 and 3 (see above).
7 (Prime)
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This note was uploaded on 01/17/2012 for the course MATH V04 taught by Professor Michaelbowen during the Spring '12 term at Ventura College.
 Spring '12
 MichaelBowen

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