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## Class 9 (Foundation)

### Course: Class 9 (Foundation)>Unit 1

Lesson 1: Rational numbers

# Classifying numbers

There are four categories in which numbers can be claified in. These categories include rational numbers, irrational numbers, integers, and whole numbers. Rational numbers are represented as a fraction of two integers, while irrational numbers cannot be represented as a fraction of two integers. Integers are numbers that don't have to be represented as a fraction or a decimal and a subset of integers are whole numbers, which are non-negative integers.

## Want to join the conversation?

• can someone give me a summary of natural numbers, whole numbers, integers, rational numbers ad irrational number please? i'm still kinda confused because i'm not sure about the differences between them
• Natural numbers:
all the whole numbers except 0

Whole numbers:
all of the counting numbers (1, 2, 3, etc.) plus 0

Integers:
(can be positive or negative)
all of the whole numbers (1, 2, 3, etc.) plus all of their opposites (-1, -2, -3, etc.) and also 0

Rational numbers:
any number that can be expressed as a fraction of two integers (like 92, -56/3, √25, or any other number with a repeating or terminating decimal)

Irrational numbers:
all the numbers that can't be expressed as a fraction of two integers (like π, √7, or any other number with a non-repeating & non-terminating decimal)

Hope this helps!
• Why is 0 considered rational if 0/0 is undefined? i guess it can be integer because its sign neutral. I would assume its just a whole number and an integer.
• The fact that 0 can be written as 0/1 is enough to show that 0 is rational.
• wait, aren't whole numbers literally the same thing as integers? and inside integers you have natural numbers, so it'd be, reals => rational and irrational, within rational => integers => natural numbers and then outside reals, complex.

how are whole numbers in any way different from integers? or natural, for that matter? or is it just a different name? but N is used for them, so it should be "natural", still.
• natural numbers contains just the positive numbers.
whole numbers are different as they contain zero in addition.
Integers are also different they contain negative numbers ,positive numbers and 0.
• How is pie over pie one!?!?!!?!?!?! Pie is inf
• While pi has an infinite number of decimal digits, pi is overall still a finite number because pi is between 3 and 4.

Any nonzero, finite number divided by itself is 1.

So pi / pi = 1.

Have a blessed, wonderful day!
• why in gods holy begotten name is this so overcomplicated
• You might think I am using a form of reverse psychology but I’m not…. Do not vote for me. …. Or am I.
• ok ill downvote dw
• What about natural numbers, and real numbers? What are those?
• Natural numbers are just positive integers (1,2,3,4,5,6,7 etc)
Real numbers are every single type of number (fractions, decimals, irrational numbers, basically anything) Best of Luck!!
• Why arn't negatives considered Whole numbers if they are numbers
• Just because something is a number doesn’t mean that it has to be a whole number. Fractions, decimals, and negatives are all numbers, but they are not whole numbers. A whole number is required to be 0 or greater and without fractional or decimal part.

Numbers without fractional or decimal part are called integers, but negative integers are not considered whole numbers.

Have a blessed, wonderful day!