🧪 Practice: Operators

Ten quick-fire exercises covering all five operator families from Module 4. Solve in practice4.py, solutions at the bottom.

Exercise 1 — The digit extractor

Ask for a 4-digit number. Print each digit on its own line using only // and %.

Exercise 2 — Even machine

Print all even numbers from 1 to 20 using % (one loop, no hardcoding).

Exercise 3 — Fix the conditions

Each condition has a bug. Fix them:

1. if age = 18:
2. if name == "Galvan" or "Admin":
3. if 0 < score and score < 100 == True:

Ask for username and password. Allow entry only if username is “admin” AND password is “open123” (case-insensitive for username).

Exercise 5 — Truth table by hand

Predict, then verify:

print(True or False and False)
print((True or False) and False)
print(not True or True)
print(5 > 3 and 2 > 4)
print(10 % 2 == 0 or 10 % 2 == 1)

Exercise 6 — Accumulate

Using only += and *=, turn x = 1 into 36 in exactly three statements (x should become 6, then 12, then 36 — wait, that’s wrong: plan your own three steps to land on 36).

Exercise 7 — The swap trick

Using only += and -= (no third variable, no tuple swap), swap a and b:

a = 5
b = 10
# your two lines here
print(a, b)    # 10 5

Exercise 8 — in or not in?

Write one line each to check:

Does the string text contain the word “python” (case-insensitive)?
Is the number 7 NOT in the list winners?
Is “email” a key in the dict user?

Exercise 9 — FizzBuzz preview

Print numbers 1 to 15. For multiples of 3 print “Fizz” instead, for multiples of 5 print “Buzz”, for multiples of both print “FizzBuzz”. (Uses % — the most famous interview warmup ever.)

Exercise 10 — Predict, then run

a = [1, 2, 3]
b = a
b += [4]
print(a)
print(a is b)

Explain both outputs.

Solutions

Exercise 1:

num = int(input("4-digit number: "))
print(num // 1000)
print(num // 100 % 10)
print(num // 10 % 10)
print(num % 10)

Exercise 2:

for n in range(1, 21):
    if n % 2 == 0:
        print(n)

Exercise 3:

if age == 18: — comparison, not assignment
if name == "Galvan" or name == "Admin": — each side needs the variable (or name in ("Galvan", "Admin"))
if 0 < score < 100: — the == True is noise, and the chain was broken

Exercise 4:

user = input("Username: ").lower()
pwd = input("Password: ")
if user == "admin" and pwd == "open123":
    print("Welcome, admin!")
else:
    print("Access denied")

Exercise 5:

True    # and binds tighter: True or (False and False)
False   # parentheses change it: True and False
True    # not True = False, False or True = True
False   # True and False
True    # 10 % 2 is 0, so the left side is True — short-circuits

Exercise 6 (one path):

x = 1
x += 5      # 6
x *= 6      # 36

Exercise 7:

a = a + b   # a=15, b=10
b = a - b   # b=5
a = a - b   # a=10

(That’s three lines — the honest answer is you need three operations without a temp variable; the tuple swap a, b = b, a is the real Pythonic one-liner.)

Exercise 8:

1. "python" in text.lower()
2. 7 not in winners
3. "email" in user

Exercise 9:

for n in range(1, 16):
    if n % 15 == 0:
        print("FizzBuzz")
    elif n % 3 == 0:
        print("Fizz")
    elif n % 5 == 0:
        print("Buzz")
    else:
        print(n)

(Check multiples of 15 FIRST — otherwise Fizz catches them early.)

Exercise 10:

[1, 2, 3, 4]
True

b = a makes b point at the SAME list as a (no copy!). b += [4] extends that shared list, so printing a shows the change too — and a is b confirms they are one object. This is your first taste of references — a big idea arriving early, courtesy of is.

✅ Module 4 Checkpoint

All ten attempted? Module 4 complete — every operator family in Python is now yours.

Next module: Data Structures — lists, tuples, sets, and dictionaries. The containers that hold everything.

🧪 Practice: Operators