Python math.sqrt() function | Find Square Root in Python (original) (raw)

Last Updated : 14 Feb, 2025

**math.sqrt() returns the **square root of a number. It is an inbuilt function in the Python programming language, provided by the math module. In this article, we will learn about how to find the square root using this function.

**Example:

Python `

import math

square root of 0

print(math.sqrt(0))

square root of 4

print(math.sqrt(4))

square root of 3.5

print(math.sqrt(3.5))

`

Output

0.0 2.0 1.8708286933869707

We need to import math before using this function.

import math

**math.sqrt() syntax

math.sqrt(x)

**Parameter:

• x: A number greater than or equal to 0.

**Returns:

• The square root of the number x.

math.sqrt() examples

Let's look at some different uses of math.sqrt() .

Example 1: Check if number is prime

math.sqrt() can be used to optimize prime number checking. We only need to check divisibility up to the square root of the number.

Python `

import math

n = 23 # Check if 23 is prime

Check if n is equal to 1

if n == 1: print("not prime") else:

# Loop from 2 to the square root of n 
for x in range(2, int(math.sqrt(n)) + 1):
    if n % x == 0:
        print("not prime")
        break  # Exit the loop
else:
    print("prime")

`

**Explanation

• If **n > 1, we check for factors from 2 to sqrt(n).
• If any divisor is found, it prints "Not prime".
• If no divisors are found, it prints "Prime".

Example 2: Finding hypotenuse of a triangle

We can use math.sqrt() to find the hypotenuse of a right-angled triangle using the Pythagorean theorem.

Python `

a = 10 b = 23 import math

c = math.sqrt(a ** 2 + b ** 2) print(c)

`

Output

The value for the hypotenuse would be 25.079872407968907

**Explanation

• The formula used is **c = sqrt(a^2 + b^2).
• It calculates the hypotenuse c using the values of **a and **b.

**Error handling

math.sqrt() does not work for negative numbers. It raises a ValueError if we pass a number less than 0.

Python `

import math

error when x<0

print(math.sqrt(-1))

`

**Output

Traceback (most recent call last):
File "/home/67438f8df14f0e41df1b55c6c21499ef.py", line 8, in
print(math.sqrt(-1))
ValueError: math domain error

**Explanation

• Square roots of negative numbers are not real numbers.
• **math.sqrt() only works with non-negative values.