Four Basic Math Rules

 What are the Four Basic Rules of Mathematics

An online basic mathematics rules printable

Four Rules of Math

The concepts of addition, subtraction, multiplication and division are complex abstract ideas which are interrelated.

1. Addition Rules:

positive + positive = (add) positive

Example: 2 + 1 = 3

negative + negative = (add) negative

Example: −3+ (−5) = −8

negative + positive = (subtract)

Example: 2 + (−10) = −8

Take sign of number with largest absolute value

Example: −14 + 16 = 2

Note: −(−7) means take the opposite of (−7) = 7

2. Subtraction Rules:

Change all subtraction to addition and take the opposite sign of the following number then follow the addition rules.

Example: −7 −(9)

means −7 +(−9) = -16

Example: −3 −(−10)

−3 + (10) = 7

Example:

−8 + (−9) −(−1)−2 (change all subtraction signs)

−8 + (−9)+ (1) + (−2) (do addition and subtraction from left to right)

−17 +(1)+ (−2)

−16 +(−2) = −18

Adding and subtracting with negative numbers:

When adding and subtracting positive and negative numbers it is useful to remember the follow-ing rules.

If the operation and the sign are the same, they work like adding a (positive) number,so that

works like ++

If the operation and the sign are different, they work like subtracting a (positive) number, sothat

+ works like −+

3 and 4. Multiplication / Division Rules:

The rules for multiplication and division are the same.

positive (✗ or ÷) positive = positive

Example: 10 ÷ 2 = 5

negative (✗ or ÷) negative = positive

Example: −4 ✗(−3) = 12

negative (✗ or ÷) positive = negative

Example: 18 ÷ (−2) −9

Multiplying and dividing with negative numbers:

When multiplying pairs of positive and negative numbers it is helpful to remember the followingrules:When the signs of the numbers are the same the answer is a positive number.

(+) ✗ (+) , answer is (+)

(−) ✗ (−) , answer is (+)

(+) ÷ (+) , answer is (+)

(−) ÷ (−) , answer is (+)

When the signs of the numbers are different the answer is a negative number.

(+) ✗ (−) , answer is (−)

(−) ✗ (+) , answer is (−)

(+) ÷ (−) , answer is (−)

(−) ÷ (+) , answer is (−)