Rules of Divisibility:

A whole number is divisible by

2 is the ones digit is 0,2,4,6, or 8.
3 if the sum of the digits of the number is divisible by 3.
4 if the last two digits of the number are divisible by 4.
5 if the ones digit is 0 or 5.
6 if the number is divisible by both 2 and 3.
9 if the sum of the digits of the number is divisible by 9.
10 if the ones digit is 0.

Greatest Common Factor
The greatest common factor is the greatest number that is a factor or two numbers. For example:
3 is the greatest common factor of 9 and 12.

Least Common Multiple
The least common multiple (LCM) is the common multiple with the least value. For example:
40 is the least common multiple of 8 and 10.

Order of Operations

 

1.  Compute inside parentheses first.

2.  Evaluate terms with exponents.

3.  Multiply and divide from left to right.

4.  Add and subtract from left to right.