Here's a summary of the number properties we're discussing @ the beginning of Chp. 2.
Commutative Properties of Addition and Multiplication
Changing the order of the numbers you're adding or multiplying won't change the answer.
Examples:
6 + 4 = 4 + 6
9 x 5 = 5 x 9
a +
b =
b +
a
a x
b =
b x
a
Associative Properties of Addition and Multiplication
If you're only adding numbers or only multiplying numbers (no other operations), changing how the numbers are grouped won't change the anwers.
Examples:
(2 + 7) + 3 = 2 + (7 + 3)
(9 x 4)5 = 9(4 x 5)
(
a +
b) +
c =
a + (
b +
c)
(
ab)
c =
a(
bc)
Identity Properties of Addition and Multiplication
Any number plus zero = the original number.
Any number times 1 = the original number.
Examples:
12 + 0 = 12
10 x 1 = 10
a + 0 =
a
a x 1 =
a
Check back later for pictures that illustrate these properties. Is everyone looking forward to Blacrock?! :)