Practice Exercises

Answer: D — All of the above

Python is a versatile, general-purpose language. It powers web frameworks like Django and Flask, drives data science with libraries like pandas and NumPy, and automates everyday tasks with simple scripts.

# Python is used everywhere:
import pandas       # Data analysis
import flask        # Web development
import os           # Automation & scripting

Answer: B

Python's syntax is designed to be readable — it uses keywords like if, for, and while instead of symbols, and indentation replaces curly braces, so code looks clean and logical.

# Python reads like English:
if temperature > 30:
    print("It's hot today!")

Answer: print

The print() function is Python's way of displaying output. Whatever you put inside the parentheses (especially in quotes) gets printed to the screen.

print("Hello, World!")  # Output: Hello, World!

Sample Solution

Each print() call creates a new line. Call print twice for two lines of output.

print("My name is Alice")
print("I love painting")
# Output:
# My name is Alice
# I love painting

Answer: B — #

In Python, the # symbol starts a single-line comment. Everything after # on that line is ignored by the interpreter. Note: // is used in C/Java, /* */ for multi-line in those languages, and -- in SQL.

# This is a comment
print("Hello")  # This is an inline comment

Answer: Use triple quotes — """ ... """

Multi-line comments in Python use triple quotes (either """ or '''). Technically these are multi-line strings, but when not assigned to a variable they act as comments.

"""
This program calculates
the area of a rectangle
"""
length = 10
width = 5
area = length * width
print(area)  # Output: 50

Sample Solution

Use = to assign values. Strings need quotes; numbers don't. Floats have a decimal point.

name = "Alice"
age = 25
height = 1.68

print(name)    # Output: Alice
print(age)     # Output: 25
print(height)  # Output: 1.68

Answer: B — 2nd_place

Variable names cannot start with a number. They must begin with a letter or underscore. After the first character, numbers are allowed.

# Valid:
my_name = "ok"
_private = "ok"
score1 = "ok"

# Invalid:
2nd_place = "error"  # SyntaxError!

Answer: B — float

Any number with a decimal point is a float (floating-point number). int has no decimal, str is text in quotes, and bool is True/False.

print(type(3.14))    # <class 'float'>
print(type(42))      # <class 'int'>
print(type("hello")) # <class 'str'>
print(type(True))    # <class 'bool'>

Sample Solution

Use type() to check a variable's data type. Remember: strings need quotes, bools are capitalized True/False.

my_int = 42
my_float = 3.14
my_str = "Python"
my_bool = True

print(type(my_int))    # <class 'int'>
print(type(my_float))  # <class 'float'>
print(type(my_str))    # <class 'str'>
print(type(my_bool))   # <class 'bool'>

Answer: int

The int() function converts a string (or float) to an integer. Without conversion, Python would treat "25" + 5 as a TypeError.

age_str = "25"
age_int = int(age_str)
print(age_int + 5)  # Output: 30

# Other conversions:
# float("3.14") → 3.14
# str(42) → "42"

Sample Solution

When you add an int and a float, Python automatically returns a float. This is called implicit type conversion.

x = 10      # int
y = 3.5     # float
result = x + y
print(result)      # Output: 13.5
print(type(result)) # Output: <class 'float'>

Answer: input

The input() function pauses the program, shows the prompt, and returns whatever the user types as a string.

color = input("What is your favorite color? ")
print("You like " + color + "!")
# If user types "blue":
# Output: You like blue!

Sample Solution

Use input() twice. Remember: input always returns a string, so if you need the age as a number, convert with int().

name = input("What is your name? ")
age = input("How old are you? ")
print("Hello " + name + ", you are " + age + " years old!")
# If user enters "Alice" and "25":
# Output: Hello Alice, you are 25 years old!

Answer: B — 14

Python follows standard math precedence (PEMDAS): multiplication before addition. So 3 * 4 = 12, then 2 + 12 = 14. Use parentheses to override: (2 + 3) * 4 = 20.

print(2 + 3 * 4)     # 14 (multiply first)
print((2 + 3) * 4)   # 20 (parentheses first)

Answer: %

The % (modulo) operator returns the remainder of division. 17 / 5 = 3 with remainder 2.

remainder = 17 % 5
print(remainder)  # Output: 2

Sample Solution

If a number % 2 equals 0, it's even; otherwise it's odd. This is the most common use of the modulo operator.

num = int(input("Enter a number: "))
if num % 2 == 0:
    print(str(num) + " is even")
else:
    print(str(num) + " is odd")
# If user enters 7: Output: 7 is odd
# If user enters 10: Output: 10 is even

Sample Solution

The if statement checks a condition. If the condition is True, the indented code block runs.

num = int(input("Enter a number: "))
if num > 0:
    print("Positive number!")
# If user enters 5: Output: Positive number!
# If user enters -3: (nothing is printed)

Answer: C — Missing colon (:) after the condition

Every if statement in Python must end with a colon. The colon tells Python "here comes the indented block."

# Correct:
if x > 10:
    print("Big")

Sample Solution

Use if…else to handle two mutually exclusive cases. The % operator checks for even/odd.

num = int(input("Enter a number: "))
if num % 2 == 0:
    print(str(num) + " is even")
else:
    print(str(num) + " is odd")
# If user enters 8: 8 is even
# If user enters 7: 7 is odd

Answer: if / else

The if keyword starts the condition check, and else catches everything that didn't match the if condition.

score = int(input("Enter your score: "))
if score >= 60:
    print("Pass!")
else:
    print("Fail!")
# score = 85 → Pass!
# score = 42 → Fail!

Sample Solution

Use elif for each additional condition. Python checks top-to-bottom and runs only the first matching block.

score = int(input("Enter your score: "))
if score >= 90:
    print("Grade: A")
elif score >= 80:
    print("Grade: B")
elif score >= 70:
    print("Grade: C")
elif score >= 60:
    print("Grade: D")
else:
    print("Grade: F")
# score = 85 → Grade: B

Sample Solution

You can use in with a list to check multiple values at once, or use range comparisons with elif.

month = int(input("Enter month (1-12): "))
if month in [3, 4, 5]:
    print("Spring")
elif month in [6, 7, 8]:
    print("Summer")
elif month in [9, 10, 11]:
    print("Autumn")
elif month in [12, 1, 2]:
    print("Winter")
else:
    print("Invalid month")
# month = 7 → Summer

Sample Solution

Place one if inside another. The inner if only runs when the outer condition is True.

num = int(input("Enter a number: "))
if num > 0:
    if num % 2 == 0:
        print("Positive and even")
    else:
        print("Positive and odd")
else:
    print("Not positive")
# num = 8 → Positive and even
# num = 7 → Positive and odd
# num = -3 → Not positive

Sample Solution

Nested if is perfect for sequential checks — first verify the username, then only proceed to the password if the username is correct.

username = input("Username: ")
if username == "admin":
    password = input("Password: ")
    if password == "python123":
        print("Access granted")
    else:
        print("Wrong password")
else:
    print("Unknown user")
# admin + python123 → Access granted
# admin + wrong → Wrong password
# other → Unknown user

Sample Solution

The leap year rule: divisible by 4 is usually a leap year, EXCEPT centuries (divisible by 100) unless also divisible by 400.

year = int(input("Enter a year: "))
if year % 400 == 0:
    print(str(year) + " is a leap year")
elif year % 100 == 0:
    print(str(year) + " is not a leap year")
elif year % 4 == 0:
    print(str(year) + " is a leap year")
else:
    print(str(year) + " is not a leap year")
# 2000 → leap year, 1900 → not, 2024 → leap year

Sample Solution

Use elif to create tiered pricing. Calculate discount as price * (1 - rate).

price = float(input("Enter total price: $"))
if price >= 200:
    final = price * 0.70  # 30% off
elif price >= 100:
    final = price * 0.80  # 20% off
elif price >= 50:
    final = price * 0.90  # 10% off
else:
    final = price         # no discount
print("Final price: $" + str(round(final, 2)))
# $150 → $120.0, $30 → $30, $250 → $175.0

Sample Solution

Use elif to handle each operator. Always check for division by zero before dividing.

a = float(input("First number: "))
op = input("Operator (+, -, *, /): ")
b = float(input("Second number: "))

if op == "+":
    print(a + b)
elif op == "-":
    print(a - b)
elif op == "*":
    print(a * b)
elif op == "/":
    if b != 0:
        print(a / b)
    else:
        print("Cannot divide by zero!")
else:
    print("Unknown operator")
# 10 / 3 → 3.333..., 5 / 0 → Cannot divide by zero!

Sample Solution

Use range(1, 11) — the end value is exclusive, so use 11 to include 10.

for i in range(1, 11):
    print(i)
# Output: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Sample Solution

You can iterate directly over a string — each iteration gives you one character.

for char in "Python":
    print(char)
# Output:
# P
# y
# t
# h
# o
# n

Sample Solution

A while loop repeats as long as its condition is True. Don't forget to update the counter variable, or you'll get an infinite loop!

count = 10
while count >= 1:
    print(count)
    count -= 1
print("Liftoff!")
# Output: 10, 9, 8, ..., 1, Liftoff!

Sample Solution

Use a while loop with a condition that checks the input. This pattern is common for menus and interactive programs.

text = ""
while text != "quit":
    text = input("Type something (quit to stop): ")
    if text != "quit":
        print("You typed: " + text)
print("Goodbye!")

Sample Solution

break immediately exits the loop. No further iterations run, and execution continues after the loop.

for i in range(1, 11):
    if i == 7:
        break
    print(i)
# Output: 1, 2, 3, 4, 5, 6

Sample Solution

continue skips the rest of the current iteration and jumps to the next one. The loop itself keeps running.

for i in range(1, 11):
    if i % 2 == 0:
        continue
    print(i)
# Output: 1, 3, 5, 7, 9

Sample Solution

The outer loop controls rows, the inner loop controls columns. Use end="\t" in print to stay on the same line.

for i in range(1, 6):
    for j in range(1, 6):
        print(i * j, end="\t")
    print()  # new line after each row
# Output:
# 1  2  3  4  5
# 2  4  6  8  10
# 3  6  9  12 15
# 4  8  12 16 20
# 5  10 15 20 25

Sample Solution

Use "*" * i to repeat the star character i times. The outer loop controls the row number.

for i in range(1, 6):
    print("*" * i)
# Output:
# *
# **
# ***
# ****
# *****

Sample Solution

The outer while loop controls rows, the inner while loop prints numbers from 1 to the current row number.

row = 1
while row <= 5:
    col = 1
    while col <= row:
        print(col, end=" ")
        col += 1
    print()  # new line
    row += 1
# Output:
# 1
# 1 2
# 1 2 3
# 1 2 3 4
# 1 2 3 4 5

Sample Solution

The inner loop's range depends on the outer loop's value, creating a shrinking countdown pattern.

outer = 3
while outer >= 1:
    inner = 3
    while inner >= outer:
        print(inner, end=" ")
        inner -= 1
    print()  # new line
    outer -= 1
# Output:
# 3
# 3 2
# 3 2 1

Sample Solution

Combine a for loop with an if statement — the loop iterates through all numbers, and the if filters only the even ones.

for num in range(1, 21):
    if num % 2 == 0:
        print(num, end=" ")
# Output: 2 4 6 8 10 12 14 16 18 20

Sample Solution

Check for "both" first (divisible by 15) — order matters! If you check 3 first, you'd miss the FizzBuzz case.

for i in range(1, 21):
    if i % 15 == 0:
        print("FizzBuzz")
    elif i % 3 == 0:
        print("Fizz")
    elif i % 5 == 0:
        print("Buzz")
    else:
        print(i)
# 1, 2, Fizz, 4, Buzz, Fizz, 7, 8,
# Fizz, Buzz, 11, Fizz, 13, 14,
# FizzBuzz, 16, 17, Fizz, 19, Buzz

Answer: B — 6

len() returns the number of items. For a string, that's the number of characters. "Python" has 6 characters: P, y, t, h, o, n.

print(len("Python"))   # 6
print(len("Hello!"))   # 6
print(len(""))         # 0
print(len([1, 2, 3]))  # 3 (works on lists too!)

Answer: print / print

type() returns the data type, and print() displays it. Both blanks need print to see the output.

x = 42
print(type(x))  # <class 'int'>
print(x)        # 42

Sample Solution

Use def to define the function, then call it by name with an argument in parentheses.

def greet(name):
    print("Hello, " + name + "!")

greet("Alice")  # Output: Hello, Alice!
greet("Bob")    # Output: Hello, Bob!

Sample Solution

This function takes no parameters — it just does the same thing every time. Functions without parameters are useful for repeated actions.

def separator():
    print("————————————")

print("Welcome")
separator()
print("Goodbye")
separator()
# Output:
# Welcome
# ————————————
# Goodbye
# ————————————

Sample Solution

Functions can have multiple parameters, separated by commas. The values you pass when calling are called arguments.

def add(a, b):
    print(a + b)

add(5, 3)    # Output: 8
add(10, 20)  # Output: 30

Sample Solution

Mix string and number parameters. Use str() to convert the number when concatenating with strings, or use f-strings for cleaner code.

def introduce(name, age):
    print("My name is " + name + " and I am " + str(age) + " years old.")

introduce("Alice", 25)
# Output: My name is Alice and I am 25 years old.

# Alternative with f-string:
def introduce(name, age):
    print(f"My name is {name} and I am {age} years old.")

Sample Solution

return sends a value back to the caller. Unlike print(), the returned value can be stored in a variable or used in further calculations.

def square(n):
    return n * n

result = square(7)
print(result)  # Output: 49

# Can also use directly:
print(square(5))  # Output: 25

Sample Solution

Use an if…else inside the function to compare the two numbers and return the larger one. The return statement immediately exits the function.

def max_of_two(a, b):
    if a >= b:
        return a
    else:
        return b

print(max_of_two(10, 20))  # Output: 20
print(max_of_two(42, 7))   # Output: 42

Sample Solution

Function composition means using one function's return value as another function's argument. Python evaluates the innermost call first: add_ten(5) = 15, then double(15) = 30.

def double(n):
    return n * 2

def add_ten(n):
    return n + 10

# Compose: first add_ten, then double
result = double(add_ten(5))
print(result)  # add_ten(5)=15, double(15)=30

# The other way:
result2 = add_ten(double(5))
print(result2)  # double(5)=10, add_ten(10)=20

Sample Solution

One function can call another inside its body. This is called function composition — circle_info delegates the calculation to circle_area and handles the display.

def circle_area(radius):
    return 3.14159 * radius * radius

def circle_info(radius):
    area = circle_area(radius)  # calls circle_area
    print("Area: " + str(round(area, 2)))

circle_info(5)   # Area: 78.54
circle_info(10)  # Area: 314.16