set theory

• set- a collection, a group of elements
• c- subset
• cardinality/cardinal- the number of items in a set, or the number of items that can be counted-

  | |/ n(a)
• repeating numbers- 0.1111- 1/9
• terminating numbers- 0.32- 32/100
• rational numbers- allow fractions, decimal, and percentages to be represented as numbers
• counting numbers- 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
• natural numbers- the set of all whole numbers, including 0 and 1
• integers- whole numbers, no decimals, no fractions
• real numbers- all real numbers are included in the set of real numbers, including the set of complex numbers
• complex numbers- a number that can be written in the form $\alpha +$$i\beta$
• P- counting, N- natural, Z- integers, Q- rational, R- real, C- complex
• P C N C Z C Q C R C C|
• EMPTY SET {} OR NULL SET O\: CONTAINS NOTHING
• INTERSECTION- ∩ common elements between two sets
• UNION- U both unique elements are combined
• compliment- everything outside of a set [']