>>> x = 1 + 2
>>> print(x)
3

>>> x = 11 // 2
>>> print(x)
5

>>> x = 2 ** 4
>>> print(x)
16

            

>>> x = int(9.6)
>>> x
9

>>> x = abs(-52)
>>> print (x)
52

            

Table. Operator Precedence from Highest to Lowest

The Precedence of the Unary Minus Depends on the Operation it is Used With.

>>> -3 ** 2
-9
>>> 3 ** -2
0.1111111111111111

            

As we can see, in the first case, the exponentiation operation is performed first, and then the unary minus is applied, while in the second case, it's the opposite.

>>> 2 + 2 * 2
6
>>> (2 + 2) * 2
8
    
                

Example: Find the sum of the digits of a two-digit number. Solution. Let 𝑥 be the given two-digit number, for example, 25. The sum of the digits of this number is the sum of its first and second digits: 2 + 5 = 7. The first digit of this number can be found by dividing the number 𝑥 by 10. The second digit of this number is the remainder of dividing the number 𝑥 by 10. Then the program will look like this:

x = int(input("Input two-digit number: "))
first_num = x // 10 
second_num = x % 10 
suma = first_num + second_num
print("The sum of the digits of a two-digit number %d = %d" % (x, suma))
        
                    

The input operation returns a string literal. Therefore, in the first line of the program, the result of the keyboard input is converted to an integer using the int instruction.

Input two-digit number: 25
The sum of the digits of a two-digit number 25 = 7
        
                    

Shorthand operators

In Python, alongside regular assignment, there exists combined operation: assignment with arithmetic action. For convenience, let's present all operators in the form of a table:

The math module contains additional functions for working with numbers. Using functions from the module implies its prior import. The module is imported as follows:

You can get a list of all methods in the math module using one of the following methods:

import math
print(dir(math))
print(help(math))
            
                        

import math
            
                        

Trigonometric functions

Complex Numbers. cmath Module.

Python can work with complex numbers. As it is known, the square root of a negative number results in a complex number. But if you use the sqrt() function from the math library to extract the square root, you won't get a complex number.

  import cmath
              
                          

Basic Functions for Complex Type

Random number generation. random module

Random numbers are most often used when necessary test the program by trying different numbers, for example, in simulators, games. To work with random numbers, you need to import the random module

• random.random() - returns a random floating-point number between 0 and 1.
• random.uniform(start, end) - returns a random floating-point number from the range specified in the parentheses. Start and end are inclusive.
• random.randint(start, end) - returns a random integer from the range specified in the parentheses. Start and end are inclusive.
• random.choice(sequence) - returns a random element from any sequence (string, list, tuple).
• random.randrange(start, end, step) - returns a randomly selected number from the sequence. Start is inclusive, end is not inclusive.

import random

print(random.random())
print(random.uniform(10, 20))
print(random.randint(10, 20))
print(random.choice('Python'))
print(random.choice([1, 2, 'a', 'b']))
print(random.choice([1, 2, 'a', 'b']))
print(random.choice((1, 3, 5, 'a')))
print(random.randrange(10, 20, 2))
              
                          

Links: Python documentation