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# What are the 3 rules for multiplying?I don't have my notebook with me and the teacher told us to write it down at home

What are the 3 rules of multiplying and the 3 rules for adding,the 1 rule for dividing and subtracting?

### 1 Answer by Expert Tutors

William F. | Math & Computer Science TutorMath & Computer Science Tutor
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Many rules exist for different types of multiplication and addition. For addition with real numbers a,b, and c:

The associative rule ensures (a+b)+c=a+(b+c)
The commutative rule ensures a+b=b+a
Property of zero ensures 0+a=a

For multiplication;
The associative rule ensures (ab)c=a(bc)
The commutative rule ensures ab=ba
The distributive rule ensures a(b+c)=ab+ac

These few rules can be extended to negative numbers and fractions, which means that they will be true under division and subtraction. A common rule of division is to not divide by 0.

Note: These rules are for real numbers. For instance, matrix multiplication is not communitive.