How to Use Math.sqrt in Java: Simple Square Root Calculation

In Java, you use Math.sqrt to find the square root of a number by passing a double value as an argument. It returns the square root as a double. For example, Math.sqrt(9) returns 3.0.

Syntax

The Math.sqrt method takes one argument, a double value, and returns its square root as a double. The argument must be non-negative; otherwise, the result will be NaN (Not a Number).

• Math.sqrt(value): Calculates the square root of value.
• value: A double number to find the square root of.
• Returns a double representing the square root.

java

double result = Math.sqrt(25);

Example

This example shows how to use Math.sqrt to calculate the square root of different numbers and print the results.

java

public class SquareRootExample {
    public static void main(String[] args) {
        double number1 = 16;
        double number2 = 2.25;
        double number3 = 0;

        System.out.println("Square root of " + number1 + " is " + Math.sqrt(number1));
        System.out.println("Square root of " + number2 + " is " + Math.sqrt(number2));
        System.out.println("Square root of " + number3 + " is " + Math.sqrt(number3));
    }
}

Output

Square root of 16.0 is 4.0
Square root of 2.25 is 1.5
Square root of 0.0 is 0.0

Common Pitfalls

Common mistakes when using Math.sqrt include:

• Passing a negative number, which returns NaN because square root of negative numbers is not defined for real numbers.
• Using integer types without converting to double, which can cause unexpected results due to integer division.

Always ensure the input is non-negative and preferably a double.

java

public class SqrtPitfall {
    public static void main(String[] args) {
        double negative = -4;
        System.out.println("Square root of -4: " + Math.sqrt(negative)); // Outputs NaN

        int intValue = 9;
        // Works fine because int is promoted to double
        System.out.println("Square root of 9: " + Math.sqrt(intValue));
    }
}

Output

Square root of -4: NaN
Square root of 9: 3.0

Quick Reference

Remember these quick tips when using Math.sqrt:

• Input must be a non-negative number.
• Returns a double value.
• Negative inputs return NaN.
• Works with integers as they are converted to double.

Key Takeaways

Use Math.sqrt to calculate the square root of a non-negative double value.

Passing a negative number to Math.sqrt returns NaN, not an error.

Math.sqrt always returns a double, even if input is an integer.

Ensure input is non-negative to avoid unexpected NaN results.

You can directly pass integer values; they are converted to double automatically.