Skills 9 Number categories notes from 8-23

Natural numbers	We counted objects in nature   1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, . . . many
Whole numbers (add the thing with the “hole”)	We invented zero to represent what is left when all is taken  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, . . .
Integers	We invented negative numbers to represent what things or money we owe . . . , -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, . . .
Rational numbers	Add fractions to the integers F R A C T I O N    R A     T I O Integer over integer except you can’t use 0 in the denominator Integer / integer An integer divided by an integer ½,     4/3,    -5/-5     0/-6     2/43
Decimals are rational	.2 = 1/5     .375 = 3/8     .94 = 94/100 Decimals are ratios with ten or a power of ten in the denominator
Rational decimals can repeat	Repeat means the same digit or set of digits repeats forever going right 1/3 = .333333333333333333333333333333333333333333333333333…
Rational decimals can terminate	Terminate means to come to an end when going right 7/8 = .875
All integers are rational	1 = 7/7    3 = 27/9   10 = 10,000/1,000   4.0 = 40/10    0 = 0/17
Not all rationals are integers	The ratio 5/12 can’t be simplified into a number
Irrational	A decimal that doesn’t repeat, and it never ends going right Pi = 3.14159. . . . . Most square roots SQRT(3)   SQRT (17) Many sides of triangles