Number Systems

Question 1

Natural numbers

Answer 1

Counting numbers. Represented by N. Whole integers, starting at 0 and increasing. Cannot have decimals or negative numbers, as that doesn’t make sense in terms of counting physical things. Like saying you have 3 dogs. Can’t have a negative amount, or half a dog.

Question 2

Integers

Answer 2

Any whole number. Represented by Z. Can be both positive and negative, but cannot be decimals. Like points on a number line.

Question 3

Real numbers

Answer 3

Any positive or negative number. Represented by R. Includes decimals and fractions. Used for measurements.

Question 4

Rational numbers

Answer 4

Numbers expressed as fractions. Represented by Q. Has to have a positive or negative integer as numerator and denominator. Can be shown as decimal. RATIOnal number. 0 cannot be denominator.

Question 5

Irrational numbers

Answer 5

Numbers that can’t be represented by a fraction. Represented as R-Q. Decimal numbers which can infinitely continue forever, with no pattern. Like pi.

Question 6

Ordinal numbers

Answer 6

Natural numbers that are used to order things. For example, 1, 2, 3, in terms of description of position in an ordered list. A is 1st, B is 2nd, etc.