4.5.1 Number Systems

Question 1

What are natural numbers?

Answer 1

A set of numbers containing all positive whole numbers and zero.

Question 2

What is a set?

Answer 2

An unordered collection of data that contains each item no more than once.

Question 3

What is the purpose of natural numbers?

Answer 3

Can be used to count how many of a certain item you have.

Question 4

What is the symbol for natural numbers?

Answer 4

ℕ.

Question 5

What are integer numbers?

Answer 5

The integers are a set of whole numbers, both positive and negative, including zero.

Question 6

What is the symbol for integers?

Answer 6

ℤ

Question 7

What are rational numbers?

Answer 7

Also called quotients, rational numbers can (but do not necessarily) have a fractional part.
They can be positive or negative, zero is a rational number.

Question 8

How can it be determined if a number is rational?

Answer 8

If a number can be written exactly as a fraction of one number over another then the number is rational.

Question 9

What is the symbol for rational numbers?

Answer 9

ℚ

Question 10

What are irrational numbers?

Answer 10

In contrast to a rational numbers, irrational numbers cannot be written exactly as a
fraction.

Question 11

What are some examples of irrational numbers?

Answer 11

Root 2
Pi
Root 3

Question 12

What is the symbol for irrational numbers?

Answer 12

Set of irrational numbers has no symbol

Question 13

What are real numbers?

Answer 13

The set of real numbers includes all possible real word quantities. It includes all of the
members of the irrational numbers, the rational numbers and hence the integers and
natural numbers too.

Question 14

What is the symbol for real numbers?

Answer 14

R

Question 15

What are ordinal numbers?

Answer 15

Ordinal numbers are integers used to describe the numerical

positions of objects in relation to others

Question 16

How do arrays use ordinal numbers?

Answer 16

Arrays index items using ordinal numbers, typically starting with an element in position 0

Question 17

What is an array?

Answer 17

A finite set of related elements of the same data type, where each element is individually indexed.

Question 18

Where might natural numbers be used?

Answer 18

Where you need to count how many of a certain object you have.

Question 19

Where might real numbers be used?

Answer 19

• Where you are measuring a quantity, you may not use whole numbers and instead use real numbers.

Question 20

What type of number do you use for counting?

Answer 20

Natural numbers

Question 21

What type of number do you use for measuring?

Answer 21

Real numbers