Practice: Operators, Booleans, and Conditionals¶

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Four practice problems, one per concept step; the numbers line up. Build each yourself, then check python-practice/solutions. Some end with a short input() "Write a Program" exercise.

Step-01: Arithmetic¶

Concepts: + - * /, //, %, **, augmented assignment (+=).

Problem-1: Two-Number Math.

Write a program that, for two numbers a = 23 and b = 4:

• Task-1: print their sum.
• Task-2: print their product.
• Task-3: print the whole-number part of a divided by b.
• Task-4: print the remainder of a divided by b.
• Task-5: print b raised to the power 2.

27
92
5
3
16

a = 23
b = 4

# Task-1: print their sum
print(a + b)
# Task-2: print their product
print(a * b)

# Task-3: print whole-number part of a // b
print(a // b)
# Task-4: print remainder of a divided by b
print(a % b)

# Task-5: print b raised to power 2
print(b ** 2)

Problem-2: Number Helpers.

Write a program that prints the absolute value of -9, then prints the quotient and remainder of 23 divided by 4 together as a pair.

9
(5, 3)

print(abs(-9))
print(divmod(23, 4))

Problem-3: Update In Place.

Write a program that:

• Task-1: starts a running total at 50, adds 25 to it, then subtracts 10 from it, and prints the result.
• Task-2: starts a counter at 0, increases it by 1 three times, and prints the result.

65
3

# Task-1: running total, add 25 then subtract 10
total = 50
total += 25
total -= 10
print(total)

# Task-2: counter from 0, add 1 three times
counter = 0
counter += 1
counter += 1
counter += 1
print(counter)

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Step-02: Comparison¶

Concepts: comparison operators, is / is None.

Problem-1: Stock Check.

Write a program that, for a stock of 72:

• Task-1: print whether stock is greater than 50.
• Task-2: print whether stock equals 72.
• Task-3: print whether stock is less than 40.
• Task-4: print whether stock is greater than or equal to 60.

True
True
False
True

stock = 72
# Task-1: print whether stock is greater than 50
print(stock > 50)
# Task-2: print whether stock equals 72
print(stock == 72)
# Task-3: print whether stock is less than 40
print(stock < 40)
# Task-4: print whether stock is at least 60
print(stock >= 60)

Problem-2: Coupon Applied?

Write a program that, for a coupon whose value is None:

• Task-1: print whether coupon is None.
• Task-2: print whether coupon is not None.

True
False

coupon = None
# Task-1: print whether coupon is None
print(coupon is None)
# Task-2: print whether coupon is not None
print(coupon is not None)

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Step-03: Boolean Logic¶

Concepts: and, or, not, in / not in, chained comparison, precedence.

Problem-1: Order Check.

Write a program that, for an order total of 30 and in_stock set to True:

• Task-1: print whether the total is above 25 and it is in stock.
• Task-2: print whether the total is above 40 or it is in stock.
• Task-3: print the opposite of in_stock.
• Task-4: print whether the letter o appears in the word order.

True
True
False
True

total = 30
in_stock = True
# Task-1: total above 25 and in stock
print(total > 25 and in_stock)
# Task-2: total above 40 or in stock
print(total > 40 or in_stock)
# Task-3: print the opposite of in_stock
print(not in_stock)

# Task-4: whether "o" appears in "order"
print("o" in "order")

Problem-2: All In Stock?

Write a program that, for a list in_stock_flags = [True, False, True] (square brackets hold several values at once; lists get a section of their own next):

• Task-1: print whether every item is true.
• Task-2: print whether at least one item is true.

False
True

in_stock_flags = [True, False, True]
# Task-1: whether every item is true
print(all(in_stock_flags))
# Task-2: whether at least one item is true
print(any(in_stock_flags))

Problem-3: More Checks.

Write a program that prints these boolean checks:

• Task-1: whether the letter z does NOT appear in the word store.
• Task-2: for a price of 85, whether it sits between 0 and 100 inclusive, written as one chained comparison.
• Task-3: the same price check written with and.
• Task-4: whether 2 + 3 equals 5 (the math runs before the comparison).

True
True
True
True

# Task-1: whether "z" is NOT in "store"
print("z" not in "store")
price = 85
# Task-2: price between 0 and 100 as chained comparison
print(0 <= price <= 100)
# Task-3: same price check written with and
print(price >= 0 and price <= 100)
# Task-4: whether 2 + 3 equals 5
print(2 + 3 == 5)

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Step-04: Making Decisions¶

Concepts: if / elif / else, the ternary (one-line if / else), nested if, %, input().

Problem-1: Shipping by Cart Total.

Write a program that, for a cart_total of 70, prints the shipping cost using if / elif / else: 0 when the total is 100 or more, 5 when it is 50 or more, 10 when it is 20 or more, and 15 otherwise.

5

# Problem-1 Task-1: shipping cost by cart total with if / elif / else
cart_total = 70
if cart_total >= 100:
    shipping = 0
elif cart_total >= 50:
    shipping = 5
elif cart_total >= 20:
    shipping = 10
else:
    shipping = 15
print(shipping)

Problem-2 (Write a Program): Pack in Pairs.

Write a program that asks for a quantity with the prompt Enter a quantity: and prints <n> packs in pairs when the number divides evenly by 2 and <n> has a leftover otherwise.

Enter a quantity: 7
7 has a leftover

# Problem-2 Task-1: pack in pairs, flag a leftover with modulo
quantity = int(input("Enter a quantity: "))
if quantity % 2 == 0:
    print(f"{quantity} packs in pairs")
else:
    print(f"{quantity} has a leftover")

Problem-3 (Write a Program): Free Shipping?

Write a program that asks for a cart total with the prompt Enter your cart total: and prints free shipping when it is 50 or more and add more otherwise.

Enter your cart total: 20
add more

# Problem-3 Task-1: free shipping when cart total is 50 or more
cart_total_in = int(input("Enter your cart total: "))
if cart_total_in >= 50:
    print("free shipping")
else:
    print("add more")

Problem-4: Order Status.

Write a program that, for is_paid set to True and is_premium set to False, prints Paid when the order is paid and then, still inside that branch, prints Premium delivery when the customer is premium and Standard delivery when not; when not paid, print Awaiting payment instead.

Paid
Standard delivery

# Problem-4 Task-1: nested order status by paid then premium
is_paid = True
is_premium = False
if is_paid:
    print("Paid")
    if is_premium:
        print("Premium delivery")
    else:
        print("Standard delivery")
else:
    print("Awaiting payment")

Problem-5: Stock Status.

Write a program that, for a units count of 0, sets status to in stock when units is above 0 and sold out otherwise, then prints status. Do it two ways: first with a regular if / else, then with the one-line if / else (the ternary).

sold out
sold out

# Problem-5 Task-1: stock status two ways, plain if / else then ternary
# Using a regular if / else
units = 0
if units > 0:
    status = "in stock"
else:
    status = "sold out"
print(status)

# Using the ternary (one-line if / else)
units = 0
status = "in stock" if units > 0 else "sold out"
print(status)

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