← Years 7–8 Creating Digital Solutions

Converting types with int() and float()

input() gives text, so int() wraps it to turn the typed text into a whole number you can calculate with. Use float() for decimals. str() turns a number back into text.

Part of: 7-8 Digital Technologies: Programming in Python — Module 8

Understanding Converting types with int() and float() in Years 7–8 Creating Digital Solutions

What it does: A number cannot be joined to a string with + until str() changes it into text. input() always gives back a string, even when the user types digits. float() keeps decimals. int() is for whole numbers, and int('4.50') causes an error. age is a string, so it must be converted with int(age) before you can add 1. After int() turns the text into numbers, + adds them. Joining '7' + '3' as strings would give '73'. int() can't convert text with a decimal point. Use float() for decimals. The fix is age = int(input("Age: ")). Then age + 1 works because age is a whole number.

Common mistakes: input() gives back text, so age + 1 would crash. Wrap it in int(): age = int(input("Age: ")). str() keeps the value as text, so score + 10 would crash. Use int() to turn the typed text into a whole number.

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Learning

Duo

A student types 5 when the program runs age = input(). What type is age?

An integer: 5A string (text): '5'

Matches

age = input("Age: ") print(age + 1)

↓

input() gives text, not a number. Adding 1 to text causes an error. Wrap input() in int() first.

Applying

Meanings

Term

int(input())

Meaning

input() gives text, so int() wraps it to turn the typed text into a whole number you can calculate with. Use float() for decimals. str() turns a number back into text.

Practice

age = int(input("Your age: "))

Testing

Gaps

age = (input("Age: "))

Check Answer

Spots

1age = input("Age: ")

2next_age = age + 1

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Quick Questions

1. A student types 5 when the program runs age = input(). What type is age?

A. A string (text): '5' ✓

B. An integer: 5

input() always gives back a string, even when the user types digits.

2. Which line lets you add 1 to the number the user types?

A. score = input(int('Score: '))

B. score = int(input('Score: ')) ✓

int() wraps around input() so the typed text is turned into a whole number.

3. Which function should you use for a price like 4.50?

A. int()

B. float() ✓

float() keeps decimals. int() is for whole numbers, and int('4.50') causes an error.

4. What does this code do? age = input('Age: ') then print(age + 1)

A. It causes an error because you can't add a number to a string ✓

B. It prints the age plus one

age is a string, so it must be converted with int(age) before you can add 1.

5. Which line prints: You are 13 years old (age is the integer 13)?

A. print('You are ' + str(age) + ' years old') ✓

B. print('You are ' + age + ' years old')

str() turns the number into text so it can be joined to other text with +.

Match the Pairs

age = int(input("Age: ")) → Asks the user to type their age, then turns the typed text into a whole number

price = float("4.50") → Turns the text "4.50" into a decimal number

Use str() to turn a number into text so it can be joined to other text with + → print("Score: " + str(score))

Convert typed text to a whole number before adding to it → total = int(input()) + 5

age = input("Age: ") print(age + 1) → input() gives text, not a number. Adding 1 to text causes an error. Wrap input() in int() first.

print("You are " + 13 + " years old") → You cannot join a number to text with +. Change the number to text using str(13).

Key Term

int(input())

input() gives text, so int() wraps it to turn the typed text into a whole number you can calculate with. Use float() for decimals. str() turns a number back into text.

Fill in the Blanks

1. age = int(input("Age: ")) print(age + 1)

Hint: Type the function that turns the typed text into a whole number.

2. price = float(input("Price: ")) print(price * 2)

Hint: Type the function that turns text into a decimal number.

3. age = 12 print("You are " + str(age) + " years old")

Hint: Type the function that turns a number into text so it can be joined to a string.

4. total = int(input("Number: ")) * 2 print(total)

Hint: Type the function that reads what the user types and gives it back as text.

5. num = int(input("Number: ")) print(num * 2)

Hint: Type the variable name that holds the converted whole number.

Spot the Error

Question 1

A age = input("Age: ")

B next_age = age + 1

C print("Next year: " + str(next_age))

Line A — input() gives back text, so age + 1 would crash. Wrap it in int(): age = int(input("Age: ")).

Question 2

A name = input("Name: ")

B score = str(input("Score: "))

C total = score + 10

D print(name, total)

Line B — str() keeps the value as text, so score + 10 would crash. Use int() to turn the typed text into a whole number.

Question 3

A print("Shopping")

B price = int(input("Price: "))

C total = price * 3

D print("Total:", total)

Line B — A price like 2.50 has a decimal point, and int() can't convert text like that. Use float() for decimal numbers.

Question 4

A n = 5

B msg = "Pets: " + n

C print(msg)

Line B — You can't join a string and an int with +. Turn the number into text first: str(n).

Question 5

A a = int(input("First: "))

B b = int(input("Second: "))

C total = a + b

D print("Sum is " + total)

Line D — total is a number, so it can't be joined to text with +. Use str(total) to turn it into text.

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