Python String isnumeric() Method

The isnumeric() method in Python checks whether all characters in a string are numeric. It returns True if all characters are numbers, and False otherwise.

Syntax

string.isnumeric()

Parameters:

• No parameters are required.

Returns:

• True – if all characters in the string are numeric
• False – if at least one character is not numeric

Example 1: Basic Usage

text = "12345"
print(text.isnumeric())

True

Example 2: String with Letters

text = "123abc"
print(text.isnumeric())

False

Example 3: Unicode Numeric Characters

text = "²³"
print(text.isnumeric())

True

These are superscript characters which are still considered numeric in Unicode.

Use Cases

• Validate if a string is a numeric ID or code
• Input validation for number-only fields
• Useful in form handling and data cleaning

Difference Between isnumeric(), isdigit(), and isdecimal()

Method	Supports Digits	Supports Unicode Numbers	Supports Decimal Characters
isnumeric()	✅	(e.g., ½, ²)	✅
isdigit()	✅	(less than isnumeric)	✅
isdecimal()	✅	❌	(only 0–9)

Common Mistakes

• Using isnumeric() on strings with spaces or punctuation returns False
• Strings with decimal points like "3.14" are not numeric by this method

Interview Tip

isnumeric() is often useful when filtering user inputs or validating data in string format.

Summary

• isnumeric() returns True if all characters in the string are numeric.
• Supports Unicode digits and numeric characters like superscripts and fractions.
• Does not recognize decimal points or negative signs as numeric.

Practice Problem

Write a program that asks the user to enter a student roll number and verifies if it's numeric:

roll = input("Enter student roll number: ")
if roll.isnumeric():
    print("Valid roll number.")
else:
    print("Invalid! Roll number must be numeric.")