2 Key takeaways

Question 1

notations for representing some fixed values in code. Python has various types of literals - for example, a literal can be a number (numeric literals, e.g., 123), or a string (string literals, e.g., “I am a literal.”).

Answer 1

Literals

Question 2

system of numbers that employs 2 as the base. Therefore, a binary number is made up of 0s and 1s only, e.g., 1010 is 10 in decimal.

Answer 2

binary system

Question 3

Octal and Hexadecimal facts

Answer 3

Octal and hexadecimal numeration systems, similarly, employ 8 and 16 as their bases respectively. The hexadecimal system uses the decimal numbers and six extra letters.

Question 4

Integers (or simply ints) are one of the numerical types supported by Python

Answer 4

They are numbers written without a fractional component, e.g., 256, or -1 (negative integers).

Question 5

one of the numerical types supported by Python. They are numbers that contain (or are able to contain) a fractional component, e.g., 1.27.

Answer 5

Floating-point numbers (or simply floats)

Question 6

To encode quote inside a string you can either use

Answer 6

escape character, e.g., ‘I'm happy.’, or open and close the string using an opposite set of symbols to the ones you wish to encode, e.g., “I’m happy.”

Question 7

to encode an apostrophe, and ‘He said “Python”, not “typhoon”’ to encode a (double) quote.

Answer 7

apostophre

Question 8

two constant objects True and False used to represent truth values (in numeric contexts 1 is True, while 0 is False.

Answer 8

Boolean Values

Question 9

There is one more, special literal that is used in Python: the None literal. This literal is a so-called NoneType object, and it is used to represent

Answer 9

the absence of a value

Question 10

“Hello “, “007”

Answer 10

strings/string literals.

Question 11

“1.5”

2.0

528

False

Answer 11

The first is a string,

second is a numerical literal (a float),

third is a numerical literal (an integer),

fourth is a boolean literal.

Question 12

What is the decimal value of the following binary number?

1011

Answer 12

It’s 11, because
(20) + (21) + (2**3) = 11

Question 13

symbol of the programming language, which is able to operate on the values.

Answer 13

operator

For example, just as in arithmetic, the + (plus) sign is the operator which is able to add two numbers, giving the result of the addition.

Question 14

operators which are associated with the most widely recognizable arithmetic operations:

Answer 14

+, -, *, /, //, %, **

Question 15

Please excuse my dear aunt sally

Answer 15

parentheses
exponents
multiplication
division
addition
subtraction

Question 16

data and operators when connected toghether form

Answer 16

expressions. The simplest expression is a literal itself.

Question 17

combination of values (or variables, operators, calls to functions ‒ you will learn about them soon) which evaluates to a certain value, e.g., 1 + 2.

Answer 17

expression

Question 18

special symbols or keywords which are able to operate on the values and perform (mathematical) operations, e.g., the * operator multiplies two values: x * y.

Answer 18

Operators

Question 19

+ (addition), - (subtraction), * (multiplication), / (classic division ‒ always returns a float), % (modulus ‒ divides left operand by right operand and returns the remainder of the operation, e.g., 5 % 2 = 1), ** (exponentiation ‒ left operand raised to the power of right operand, e.g., 2 ** 3 = 2 * 2 * 2 = 8), // (floor/integer division ‒ returns a number resulting from division, but rounded down to the nearest whole number, e.g., 3 // 2.0 = 1.0)

Answer 19

Arithmetic operators in Python

Question 20

operator is an operator with only one operand, e.g., -1, or +3.

Answer 20

unary

Question 21

operator is an operator with two operands, e.g., 4 + 5, or 12 % 5.

Answer 21

binary

Question 22

Some operators act before others – the hierarchy of priorities:

Answer 22

the ** operator (exponentiation) has the highest priority;

then the unary + and - (note: a unary operator to the right of the exponentiation operator binds more strongly, for example: 4 ** -1 equals 0.25)

then *, /, //, and %;

and, finally, the lowest priority: the binary + and -.

Question 23

are always calculated first, e.g., 15 - 1 * (5 * (1 + 2)) = 0.

Answer 23

Subexpressions in parentheses

Question 24

The exponentiation operator uses

Answer 24

right-sided binding, e.g., 2 ** 2 ** 3 = 256.

Question 25

print((2 ** 4), (2 * 4.), (2 * 4))

Answer 25

16 8.0 8

Question 26

print((-2 / 4), (2 / 4), (2 // 4), (-2 // 4))

Answer 26

-0.5 0.5 0 -1

Question 27

print((2 % -4), (2 % 4), (2 ** 3 ** 2))

Answer 27

-2 2 512

Question 28

(2 ** 3 ** 2))

 same as

2 ** (3 ** (2 ** 1))

Answer 28

2 ** (3 ** (2 ** 1))

= 2 ** (3 ** 2)
= 2 ** 9
= 512

Question 29

named location reserved to store values in the memory. A variable is created or initialized automatically when you assign a value to it for the first time. (2.1.4.1)

Answer 29

Variable

Question 30

A legal identifier name must be a non-empty sequence of characters, must begin with the underscore(_), or a letter, and it cannot be a Python keyword. The first character may be followed by underscores, letters, and digits. Identifiers in Python are case-sensitive. (2.1.4.1)

Answer 30

Each variable must have a unique name - an identifier

Question 31

means you don’t need to declare variables in it. (2.1.4.3) To assign values to variables, you can use a simple assignment operator in the form of the equal (=) sign, i.e., var = 1.

Answer 31

Python is a dynamically-typed language

Question 32

(shortcut operators) to modify values assigned to variables, e.g., var += 1, or var /= 5 * 2. (2.1.4.8)

Answer 32

You can also use compound assignment operators

Question 33

You can assign new values to already existing variables using the assignment operator or one of the compound operators, e.g.: (2.1.4.5)

Answer 33

var = 2
print(var)

var = 3
print(var)

var += 1
print(var)

Question 34

You can combine text and variables using the + operator, and use the print() function to output strings and variables, e.g.: (2.1.4.4)

Answer 34

var = “007”
print(“Agent “ + var)

Question 35

var = 2
var = 3
print(var)

Answer 35

3

Question 36

my_var
m
101
averylongvariablename
m101
m 101
Del
del

Answer 36

my_var
m
101 # incorrect (starts with a digit)
averylongvariablename
m101
m 101 # incorrect (contains a space)
Del
del # incorrect (is a keyword)

Question 37

a = ‘1’
b = “1”
print(a + b)

Answer 37

11

Question 38

a = 6
b = 3
a /= 2 * b
print(a)

Answer 38

1.0

2 * b = 6
a = 6 → 6 / 6 = 1.0

Question 39

function sends data to the console

Answer 39

print()

Question 40

gets data from console

Answer 40

input()

Question 41

function comes with an optional parameter: the prompt string. It allows you to write a message before the user input, e.g.:

name = input(“Enter your name: “)
print(“Hello, “ + name + “. Nice to meet you!”)

Answer 41

input()

Question 42

When the input() function is called, the program’s flow is stopped

Answer 42

the prompt symbol keeps blinking (it prompts the user to take action when the console is switched to input mode) until the user has entered an input and/or pressed the Enter key.