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Numbers are used everywhere in programming.
You may use numbers to:
Python provides three important built-in numeric types:
| Type | Name | Example | Common Use |
|---|---|---|---|
int | Integer | 25 | Whole numbers |
float | Floating-point | 25.5 | Decimal values |
complex | Complex number | 3 + 4j | Scientific and engineering calculations |
Let's understand each one step by step.
int)An integer is a whole number without a decimal part.
Examples:
All of these values are integers.
Output:
Integers can be positive, negative, or zero.
Imagine counting physical objects.
If you have 10 books:
You can have:
But normally, you don't say:
That's why counting objects commonly uses integers.
One useful feature of Python is that integers can grow much larger than the typical fixed-size integers used in many other programming languages.
For example:
Output:
Python can handle this large integer without the usual fixed 32-bit integer limit.
You can also check how many digits it has:
Output:
Large numbers can be difficult to read.
Compare:
with:
Both represent exactly the same number.
Output:
Python simply ignores the underscores when reading numeric literals.
For large numbers, use underscores:
This is easier to read than:
Python also allows integers to be written in different number systems.
Prefix: 0b
Output:
Prefix: 0o
Output:
Prefix: 0x
Output:
These are especially useful when working with computers, networking, colors, and low-level programming.
float)A float is a number that can contain a decimal part.
Examples:
Check the type:
Output:
Suppose you are measuring the weight of gold:
The value contains a decimal part, so a float is useful.
Other examples:
Python also supports scientific notation using e or E.
For example:
This means:
So:
Output:
You can also represent very small numbers:
Output:
Scientific notation is useful for very large or very small numbers.
You may notice something surprising in Python:
Output:
You may expect:
Why does this happen?
Computers store floating-point numbers using binary representation.
Some decimal values, such as 0.1 and 0.2, cannot be represented exactly in binary floating-point format.
So Python stores a very close approximation.
This is not a Python bug.
It is a normal limitation of binary floating-point arithmetic.
Because of this behavior, avoid relying on exact equality when comparing calculated floating-point values.
For example:
Output:
Instead, Python provides math.isclose() for checking whether two numbers are sufficiently close.
Output:
math.isclose() allows a small difference caused by floating-point representation.
round() vs math.isclose()These two functions solve different problems.
round()Use round() when you want to control the displayed or stored rounded value:
Output:
math.isclose()Use math.isclose() when you want to compare two calculated values:
Output:
round() is useful for rounding.
math.isclose() is useful for comparing floating-point results.For many simple examples, float is fine.
However, financial applications may need exact decimal arithmetic.
For example:
Python provides the decimal.Decimal type for such situations.
Example:
Output:
For now:
int for whole numbers.float for normal decimal calculations.Decimal later when you work with precise financial calculations.complex)A complex number contains two parts:
In mathematics, complex numbers are commonly written as:
Python uses j instead of i.
For example:
Here:
j?Python uses j or J to represent the imaginary part.
Correct:
Also correct:
Incorrect:
Python does not use i as the imaginary-number suffix.
You can create a complex number directly:
Output:
You can also use the complex() function:
Output:
Python provides .real and .imag.
Output:
Notice that these values are returned as floats.
Python supports normal arithmetic with complex numbers.
Output:
The conjugate changes the sign of the imaginary part.
For example:
becomes:
Python:
Output:
The magnitude of:
is:
which equals:
Python can calculate it using abs():
Output:
This is similar to finding the length of the hypotenuse of a right triangle.
Complex numbers are commonly used in areas such as:
For example, electrical engineers can represent impedance as:
where:
R = resistanceX = reactancej = imaginary unitPython's built-in complex type makes these calculations easier.
| Situation | Recommended Type | Example |
|---|---|---|
| Number of students | int | 50 |
| Age | int | 21 |
| Product quantity | int | 5 |
| Temperature | float | 36.5 |
| Product price | float | 99.99 |
| Scientific measurement | float | 1.5e8 |
| Electrical impedance | complex | 40 + 5j |
| Precise currency calculation | Decimal | Decimal("99.99") |
Let's combine what we learned:
Possible output:
| Situation | Don't | Do |
|---|---|---|
| Large numbers | 15000000 | 15_000_000 |
| Float comparison | total == 0.3 | math.isclose(total, 0.3) |
| Complex numbers | 3 + 4i | 3 + 4j |
| Imaginary value | 5 + j | 5 + 1j |
| Precise financial calculations | Rely blindly on float | Consider Decimal |
math.isclose() when appropriate for comparisonsj.real gets the real part.imag gets the imaginary part.conjugate() returns the conjugateabs() returns the magnitude0.1 + 0.2 produce 0.30000000000000004?Create a small program that demonstrates all three Python numeric types.
Your program should:
math.isclose() to compare a calculated value.After running the program, try changing:
to another integer.
Then change:
to another decimal value.
Finally, experiment with:
For example:
Observe how the real part, imaginary part, and magnitude change.
In this lesson, you learned:
int represents whole numbersfloat represents decimal valuesmath.isclose() helps compare floating-point valuesDecimal may be useful for financial calculationsj.real and .imagIn the next lesson, we will continue your Python learning journey with Mathematical Operations (4: Numbers).
Continue learning with hands-on practice, examples, and exercises in the upcoming topic.
| Previous Lesson | Next Lesson |
|---|---|
| Checking Data Types (isinstance) | Mathematical Operations |
Test your understanding of this lesson with 6 questions. Each question has one correct answer.