Numeric values (int and float behavior) in Python

Introduction

Numbers help us count and measure things in programs. Integers (int) are whole numbers, and floats are numbers with decimals.

When you need to count items like apples or books (use int).

When you measure something like weight or height that can have decimals (use float).

When you want to do math like adding, subtracting, multiplying, or dividing numbers.

When you want to store and use numbers in your program for calculations.

When you want to convert between whole numbers and decimal numbers.

Syntax

Python

integer_number = 10
float_number = 3.14

Integers are written without a decimal point.

Floats have a decimal point or use scientific notation like 1e3 (which means 1000).

Examples

This shows how Python treats numbers as int or float based on their form.

Python

a = 5
b = 2.0
print(type(a))  # <class 'int'>
print(type(b))  # <class 'float'>

You can convert an integer to a float using float().

Python

x = 7
y = float(x)
print(y)  # 7.0

Converting a float to int cuts off the decimal part (does not round).

Python

z = 4.5
w = int(z)
print(w)  # 4

Sample Program

This program shows adding and multiplying int and float numbers, and converting between them.

Python

num1 = 8
num2 = 3.5
sum_result = num1 + num2
product = num1 * num2
int_conversion = int(num2)
float_conversion = float(num1)

print(f"Sum: {sum_result}")
print(f"Product: {product}")
print(f"Integer conversion of {num2}: {int_conversion}")
print(f"Float conversion of {num1}: {float_conversion}")

Important Notes

Adding an int and a float results in a float.

Converting float to int removes decimals without rounding.

Use float when you need decimals, int when you want whole numbers only.

Summary

Integers are whole numbers without decimals.

Floats are numbers with decimals.

You can convert between int and float using int() and float().

Practice

1.

Which of the following is an example of a float in Python?

1. 42
2. 3.14
3. -7
4. 0

easy

A. 42

B. 3.14

C. -7

D. 0

Solution

1. Step 1: Understand what a float is

   A float is a number with a decimal point, like 3.14.

2. Step 2: Identify the float among options

   Only 3.14 has a decimal point, so it is a float.

3. Final Answer:

   3.14 -> Option B

4. Quick Check:

   Float = 3.14 [OK]

Hint: Floats always have a decimal point [OK]

Common Mistakes:

• Choosing integers as floats
• Confusing negative numbers with floats
• Ignoring decimal points

2.

Which of the following is the correct way to convert the float 5.7 to an integer in Python?

easy

A. float(5.7)

B. int(5,7)

C. int('5.7')

D. int(5.7)

Solution

1. Step 1: Recall how to convert float to int

   Use the int() function with a float value as argument.

2. Step 2: Check each option

   int(5.7) correctly converts float 5.7 to int 5. int('5.7') causes error, int(5,7) is invalid syntax.

3. Final Answer:

   int(5.7) -> Option D

4. Quick Check:

   int(5.7) = 5 [OK]

Hint: Use int() directly on float to convert [OK]

Common Mistakes:

• Trying int() on string with decimal
• Using wrong syntax like int(5,7)
• Using float() instead of int()

3.

What is the output of the following code?

x = 7 / 2
print(type(x))
print(x)

medium

A. <class 'int'>\n3.5

B. <class 'int'>\n3

C. <class 'float'>\n3.5

D. SyntaxError

Solution

1. Step 1: Understand division operator in Python 3

   Division with / always returns a float, even if numbers divide evenly.

2. Step 2: Evaluate the code

   7 / 2 = 3.5, which is a float. So type(x) is <class 'float'> and x is 3.5.

3. Final Answer:

   <class 'float'>\n3.5 -> Option C

4. Quick Check:

   7 / 2 = 3.5 float [OK]

Hint: Division / always returns float in Python 3 [OK]

Common Mistakes:

• Assuming integer division with /
• Confusing type output format
• Expecting 3 instead of 3.5

4.

Find the error in this code snippet:

num = 4.8
num_int = int(num)
print(num_int + ' is the integer value')

medium

A. Cannot add int and str directly

B. No error, code runs fine

C. Syntax error in print statement

D. Cannot convert float to int

Solution

1. Step 1: Check conversion from float to int

   int(4.8) converts float 4.8 to int 4 without error.

2. Step 2: Check print statement

   Adding int and string directly causes a TypeError in Python.

3. Final Answer:

   Cannot add int and str directly -> Option A

4. Quick Check:

   int + str causes TypeError [OK]

Hint: Convert int to str before adding to string [OK]

Common Mistakes:

• Thinking int() conversion fails
• Ignoring type mismatch in addition
• Assuming print syntax error

5.

You have a list of mixed numbers: nums = [1, 2.5, 3, 4.75, 5]. You want to create a new list with all numbers converted to integers by dropping decimals. Which code correctly does this?

hard

A. new_nums = [int(n) for n in nums]

B. new_nums = [float(n) for n in nums]

C. new_nums = [str(int(n)) for n in nums]

D. new_nums = [round(n) for n in nums]

Solution

1. Step 1: Understand the goal

   We want to convert all numbers to int by dropping decimals, not rounding.

2. Step 2: Evaluate each option

   C uses int() which drops decimals correctly. A converts to string, not int. B converts to float, not int. D rounds numbers, which changes values.

3. Final Answer:

   new_nums = [int(n) for n in nums] -> Option A

4. Quick Check:

   int() drops decimals, list comprehension applies to all [OK]

Hint: Use int() in list comprehension to drop decimals [OK]

Common Mistakes:

• Using round() instead of int()
• Converting to string instead of int
• Using float() which keeps decimals