Chapter 0 · Section 5 practice
Functions
Work from question 1 to 10. Write your code, click Run Code, review the result, then click Submit attempt. An attempt may be wrong: reference answers become available after you submit all 10. Each Python box is independent. Submission progress is saved in this browser.
1. Define and call
Warm-up. Define double(number) to return twice its input. Print double(4).
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2. Reuse a result
Warm-up. Define add_five(number), store add_five(10) in result, then print result and result * 2.
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3. Two parameters
Warm-up. Define rectangle_area(length, width). Print the areas for (5, 3) and (2.5, 4).
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4. Label the arguments
Build your skills. Define ticket_bill(price, quantity). Call it using named arguments quantity=3 and price=25, and print the result.
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5. Repair print versus return
Build your skills. The function should provide a number that can be stored and multiplied. Replace the display instruction inside the function with a return, then print result * 2.
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6. A fee as an input
Build your skills. Define net_sale(price, shares, fee_rate). Return price * shares minus that amount times fee_rate. Print the results at price 100, shares 10, fees 0 and 0.001.
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7. Convert inside a function
Build your skills. Define bill_from_text(price_text, quantity_text). Convert the inputs and return the numeric bill. Print its result for “12.50” and “4” with two decimal places.
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8. Choose a delivery charge
Challenge. Define delivery_fee(order_value): return 0 if the value is at least 100, otherwise return 15. Print the fees for 80, 100, and 120.
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9. Call a function in a loop
Challenge. Define passes(score) to return whether score is at least 60. Loop over the scores, printing each score and the returned Boolean.
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10. A discounted bill with delivery
Challenge. Define final_bill(price, quantity, discount_rate). Subtract the discount from the product cost, then add HK$15 delivery only if the discounted bill is below HK$100. Print bills for (40, 3, 0.1) and (25, 2, 0.1) with two decimals.
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Reference answers are locked until all 10 attempts are submitted.
1. Define and call
def double(number):
return number * 2
print(double(4))Expected output
8def defines the instructions; a call supplies the input and runs them.
2. Reuse a result
def add_five(number):
return number + 5
result = add_five(10)
print(result)
print(result * 2)Expected output
15
30return gives a number back to the caller; print alone would not return that number.
3. Two parameters
def rectangle_area(length, width):
return length * width
print(rectangle_area(5, 3))
print(rectangle_area(2.5, 4))Expected output
15
10.0Both inputs matter; a float input can produce a float area.
4. Label the arguments
def ticket_bill(price, quantity):
return price * quantity
print(ticket_bill(quantity=3, price=25))Expected output
75Named arguments identify the matching parameter even when written in a different order.
5. Repair print versus return
def triple(number):
return number * 3
result = triple(4)
print(result * 2)Expected output
24The original function displays a value and returns None. Returning the calculation lets the caller use 12.
6. A fee as an input
def net_sale(price, shares, fee_rate):
gross = price * shares
fee = gross * fee_rate
return gross - fee
print(net_sale(100, 10, 0))
print(net_sale(100, 10, 0.001))Expected output
1000
999.0The same function handles both assumptions. A 0.001 rate means a 0.1% commission.
7. Convert inside a function
def bill_from_text(price_text, quantity_text):
price = float(price_text)
quantity = int(quantity_text)
return price * quantity
bill = bill_from_text("12.50", "4")
print(f"HK${bill:.2f}")Expected output
HK$50.00Conversion and calculation happen inside the function; formatting happens at the call site.
8. Choose a delivery charge
def delivery_fee(order_value):
if order_value >= 100:
return 0
else:
return 15
print(delivery_fee(80))
print(delivery_fee(100))
print(delivery_fee(120))Expected output
15
0
0The equality boundary qualifies for free delivery under this classroom rule.
9. Call a function in a loop
def passes(score):
return score >= 60
scores = [55, 60, 85]
for score in scores:
print(score, passes(score))Expected output
55 False
60 True
85 TrueFunctions can return Boolean values, not only numbers.
10. A discounted bill with delivery
def final_bill(price, quantity, discount_rate):
subtotal = price * quantity
bill = subtotal * (1 - discount_rate)
if bill < 100:
bill = bill + 15
return bill
print(f"HK${final_bill(40, 3, 0.1):.2f}")
print(f"HK${final_bill(25, 2, 0.1):.2f}")Expected output
HK$108.00
HK$60.00The first discounted bill is 108 and gets no delivery fee; the second is 45 and gets a 15 fee.