← Python

F-String Formatting

An f-string embeds variable values directly inside a string using the f"...{variable}..." syntax

What it does: int() converts a numeric string to an integer. str() converts a number to a string — useful for concatenation. int() truncates — it cuts off the decimal, it does not round. str() always produces a string — not a float. float() adds a decimal point — the integer 5 becomes 5.0. Python can't add a string and a number — use int('5') + 3 instead. int('10') converts '10' to the number 10, then 10 + 5 = 15. str(5) converts 5 to a string — type() then reports it as 'str'.

Common mistakes: Line 2 should use int() not str(). Use: number = int(text). Line 2 can't add string + int. Convert first: next_age = int(age) + 1.

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Learning

Duo

What does int("5") return?

5"5"

Matches

❌ int('hello')

↓

Error: Cannot convert to int

Applying

Meanings

Term

int("5")

Meaning

Converts the string "5" to the integer 5.

Practice

cm = int("42")

Testing

Gaps

number = ("42")

Check Answer

Spots

1text = "42"

2number = str(text)

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Quick Questions

1. What does int("5") return?

A. 5 ✓

B. "5"

int() converts a string of digits into an actual integer

2. What does str(42) return?

A. 42

B. "42" ✓

str() converts a number into a string — strings have quote marks

3. What does float("3.14") return?

A. 3.14 ✓

B. "3.14"

float() converts a string like '3.14' into the floating-point number 3.14

4. What does int(3.9) return?

A. 4

B. 3 ✓

int() truncates — it cuts off the decimal, it does not round

5. What does str(100) convert 100 to?

A. A string ✓

B. A float

str() always produces a string — not a float

Match the Pairs

int('hello') → Error: Cannot convert to int

x = '5' print(x + 3) → Error: str + int not allowed

int('42') → Valid: Returns 42

str(100) → Ok: Returns '100'

print(int(3.9)) → Output: 3

print(float('2.5')) → Output: 2.5

Key Term

int("5")

Converts the string "5" to the integer 5.~~float("3.14")

Fill in the Blanks

1. number = int("42")

2. text = str(100)

3. decimal = float("300")

4. year = input() year = int(year)

5. score = 95 result = str(score) print(result)

Spot the Error

Question 1

A text = "42"

B number = str(text)

C print(number + 1)

Line B — Line 2 should use int() not str(). Use: number = int(text)

Question 2

A age = input("Enter age: ")

B next_age = age + 1

C print(next_age)

Line B — Line 2 can't add string + int. Convert first: next_age = int(age) + 1

Question 3

A score = 95

B message = "Score: " + score

C print(message)

Line B — Line 2 can't join string + int. Use: message = "Score: " + str(score)

Question 4

A value = "3.14"

B decimal = Int(value)

C print(decimal)

Line B — Line 2 uses Int() with capital I. Python is case-sensitive. Use: int(value)

Question 5

A int("7")

B num = "7"

C print(num + 3)

Line A — Converts but doesn't save the result. Use: num = int(num)

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