Number
Content
The Meaning of Numbers
The term number comes from the Latin "numĕrus" and refers to the expression of a quantity in relation to its unit, therefore, it is an expression of the relation between quantity and unit. The science focused on the study of numbers that corresponds to their properties and the operations that can be performed with them is arithmetic, which is a main branch of mathematics.
Knowing how to understand numbers helps us in our lives and that is why there is a science known as numerology, which is responsible for studying the meaning of numbers and their relationship with everything around us.
Classification of the numbers
The numbers are classified into five main types:

Natural numbers: They are represented with an "N", corresponds to any number that is greater than zero (0), in other words any positive number. It is important to consider that natural numbers cannot have a decimal, fractional, or imaginary part. N = [1, 2, 3, 4,…, + infinity)
Learn more about: “Natural numbers”. →
Note: Some authors include zero as a natural number.

Integer numbers: They are represented with a "Z", corresponds to any natural number, to zero and negative numbers are included. Since they must be integers, they cannot have a decimal, fractional, or imaginary part. Z = ( infinity,…, 2, 1, 0, 1, 2,…, + infinity)
Learn more about: “Integer numbers”. →

Rational numbers: They are represented with a "Q", they are those whose numbers can be expressed as a fraction of two whole numbers. Q = [1/2, 3/1, 8/4, 5/4, 1/3, etc.]
Learn more about: “Rational numbers”. →
 Real numbers: They are represented with an "R", these include both rational numbers and irrational numbers. R = [Q, irrational]
Learn more about: “Irrational numbers”. →
 Complex numbers: They are represented with a "C", include all types of previous numbers plus the imaginary number "i". C = [N, Z, Q, R, i]
Learn more about: “Complex numbers”. →
Even numbers
Any integer that can be divided by 2, in other words would be to obtain half of a number with a residue of 0 or no decimal points. You can also identify an even number if the last digit or the unit is 0, 2, 4, 6 or 8. Example: 38 is an even number since the last digit is 8, if at 38 we divide it by 2 the result is 19, other even numbers: 20, 6, 16 and 34 are all even numbers.
Learn more about: “Pair numbers”. →
Odd numbers
An odd number can be easily identified if the last digit is 1, 2, 5, 7 or 9. Example: 35, 27, 49, and  33 are odd numbers.
Learn more about: “Odd numbers”. →
Prime numbers
Prime numbers are numbers that are only divisible between themselves and 1.
Learn more about: “Prime numbers”. →
Numbers with decimals
They are numbers that have a decimal part.
Learn more about: “Decimals”. →
Ordinal numbers
They are those that denote a position of an element or set of elements in an ordered sequence.
Learn more about: “Ordinal numbers”. →
PI number
The number pi is the relationship between the perimeter of a circle and the length of its diameter, it is considered as an irrational number.
Learn more about: “PI number”. →
Golden Number
The Golden number or gold number, is an irrational number, is a number that has many interesting properties.
Learn more about: “Golden Number”. →
Euler Number
The Euler number is a mathematical constant and belongs to the most important irrational numbers.
Learn more about: “Euler Number”. →
Content
Arithmetic Tutorials
 Arithmetic
 Number
 Natural
 Integer
 Rational
 Irrational
 Complex
 Even
 Odd
 Prime
 Decimal
 Ordinal
 Pi number
 Euler number
 Golden number
 Place value
 Sum
 Subtraction
 Multiplication
 Division
 Rule of signs
 Signs of greater and lesser
 Absolute value
 Fraction
 Multiples
 Least common multiple (lcdm)
 Divisor
 Greatest common divisor (gcd)
 Exponent
 Logarithm
 Root (square y cube)
 Factorial
 Percentage
 Rule of three