statement (proposition)
a sentence that is either true or false but not true and false
conditional statement
a statement that can be written in the form "If P then Q" where P and Q are sentences (P is the hypothesis and Q is the conclusion)
even integer
an integer a where there exists an integer n so that a = 2n
odd integer
an integer a where there exists an integer n so that a = 2n + 1
natural numbers, N
positive whole numbers
integers, Z
closed under addition, multiplication, and subtraction, positive and negative
rational numbers, Q
real numbers that can be written as a quotient of two integers
real numbers, R
all real numbers; rational and irrational numbers