Learning these divisibility rules can help you a great deal when finding the factors of a number.
These rules can also help when finding the LCM and GCF
Divisible by 2
The number ends in an even number then it is divisible by 2
Divisible by 3
Add the digits of the number together and if the sum is divisible by 3 the entire number is divisible by 3
Divisible by 4
If the last two digits are divisible by 4 then the original number is divisible by 4
Divisible by 5
If the number ends in 5 or 0 then the number is divisible by 5
Divisible by 6
If the number is divisible by 2 or 3 then the number is also divisible by 6
Divisible by 7
Multiply the last digit by 2 then subtract this from the remaining number, if this number is zero or divisible by 7 then the number is divisible by 7.
Example: 168
8 x 2 = 16
16-16 = 0 16 is the remaining number when you take the 8 away
7 x 24 = 168
Divisible by 8
Divide the number by 2 twice, if this number is even, then the number is divisible by 8
64 64/2 = 32
32/2 = 16 which even so 64 is divisible by 8
8 x 8 = 64
Divisible by 9
If the sum of the digits is divisible by 9 then the number is divisible by 9
72 7+2 = 9
9 /9 = 1
9 x 8 = 72
Divisible by 10
If the number ends in zero, the number is divisible by 10
If the number is divisible by 2 or 3 then the number is also divisible by 6
Divisible by 7
Multiply the last digit by 2 then subtract this from the remaining number, if this number is zero or divisible by 7 then the number is divisible by 7.
Example: 168
8 x 2 = 16
16-16 = 0 16 is the remaining number when you take the 8 away
7 x 24 = 168
Divisible by 8
Divide the number by 2 twice, if this number is even, then the number is divisible by 8
64 64/2 = 32
32/2 = 16 which even so 64 is divisible by 8
8 x 8 = 64
Divisible by 9
If the sum of the digits is divisible by 9 then the number is divisible by 9
72 7+2 = 9
9 /9 = 1
9 x 8 = 72
Divisible by 10
If the number ends in zero, the number is divisible by 10
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