Section 2.1 Properties of Numbers Algebra Concepts Section 2.1 Properties of Numbers

Commutative property of addition- changing the order of numbers you are adding does not change the sum. 2+1=3 1+2=3

This is true for all real numbers. Think of different examples for a and b

Commutative property of multiplication- changing the order when multiplying does not change the product.

This is true for all real numbers. Think of different examples for a and b.

Associative property of addition-changing the grouping of values you are adding does not change the sum.

Make a problem easier with associative property! 4+ 6+72 +7+(3+8) 4+6 +72+ 7+3 +8 10+72+10+8 92

This works for all real numbers BUT all operation signs must be addition.

Associative property of multiplication-changing the grouping of values you are multiplying does not change the product.

Make a problem easier with associative property! 5× 2×43 5×2 ×43 10×43 430

This works for all real numbers BUT all operation signs must be multiplication.

Additive identity=0 Identity property of addition- the sum of 0 and any number is always the original number.

This works for all real numbers. Think of some examples with natural #s, integers and rational #s

Multiplicative identity= 1 Identity property of multiplication- the product of any number and 1 is the original number.

This works for all real numbers.

Name that property! #1 3+5=5+3 #2 7+0=7 #3 2× 4×5 =(2×4)×5 #4 −8 1 =−8 #5 4×3=3×4

Mental math When you don’t have a calculator, the properties help you find an answer. #1 5+28+15 #2 (97+8)+2 #3 $1.50 + $.83 + $.50