Java Academy · Lesson

BigInteger for Huge Numbers

Arbitrary-precision integers.

BigInteger for Huge Numbers is a free Java Academy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Java Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Beyond long

The primitive long can hold values up to about 9.2 quintillion. When you need integers larger than that, Java offers BigInteger from the java.math package, which has no fixed upper limit.

When long Overflows

Exceeding Long.MAX_VALUE silently wraps around to a negative number. This corruption is a classic bug source.

public class Main {
    public static void main(String[] args) {
        long max = Long.MAX_VALUE;
        System.out.println(max);
        System.out.println(max + 1);
    }
}

Creating a BigInteger

Build a BigInteger from a string of digits. There is no length limit, so you can write numbers far larger than any primitive.

import java.math.BigInteger;

public class Main {
    public static void main(String[] args) {
        BigInteger huge = new BigInteger("123456789012345678901234567890");
        System.out.println(huge);
    }
}

From a long With valueOf

If your starting value fits in a long, BigInteger.valueOf is a convenient factory method.

import java.math.BigInteger;

public class Main {
    public static void main(String[] args) {
        BigInteger n = BigInteger.valueOf(1000000);
        System.out.println(n);
    }
}

Immutable Arithmetic

Like BigDecimal, BigInteger is immutable. add, subtract, and multiply return new objects you must capture.

import java.math.BigInteger;

public class Main {
    public static void main(String[] args) {
        BigInteger a = new BigInteger("99999999999999999999");
        BigInteger b = BigInteger.valueOf(1);
        System.out.println(a.add(b));
    }
}

Multiplying Big Numbers

Multiplication that would overflow a long works fine with BigInteger.

import java.math.BigInteger;

public class Main {
    public static void main(String[] args) {
        BigInteger a = new BigInteger("10000000000");
        BigInteger b = new BigInteger("10000000000");
        System.out.println(a.multiply(b));
    }
}

Computing a Factorial

Factorials grow explosively. Even 30 factorial overflows a long, but BigInteger handles it easily.

import java.math.BigInteger;

public class Main {
    public static void main(String[] args) {
        BigInteger result = BigInteger.ONE;
        for (int i = 1; i <= 30; i++) {
            result = result.multiply(BigInteger.valueOf(i));
        }
        System.out.println(result);
    }
}

Power and Modulo

pow raises a value to an integer exponent, and mod gives the remainder. Both are common in cryptography.

import java.math.BigInteger;

public class Main {
    public static void main(String[] args) {
        BigInteger base = BigInteger.valueOf(2);
        System.out.println(base.pow(64));
        System.out.println(base.pow(10).mod(BigInteger.valueOf(7)));
    }
}

Comparing Values

Use compareTo to order two BigInteger values. It returns a negative number, zero, or a positive number.

import java.math.BigInteger;

public class Main {
    public static void main(String[] args) {
        BigInteger a = new BigInteger("500");
        BigInteger b = new BigInteger("1000");
        System.out.println(a.compareTo(b));
    }
}

Handy Constants

BigInteger provides ZERO, ONE, TWO, and TEN. Use them as starting accumulators or in loops.

import java.math.BigInteger;

public class Main {
    public static void main(String[] args) {
        BigInteger sum = BigInteger.ZERO;
        sum = sum.add(BigInteger.TEN).add(BigInteger.ONE);
        System.out.println(sum);
    }
}

When to Reach for It

Use BigInteger for factorials, very large counters, cryptographic keys, and anywhere a result might exceed long. For ordinary counting, stick with primitives since they are far faster.

Quick Check

Test your BigInteger understanding.

Recap

You learned to use BigInteger:

long overflows silently, but BigInteger has no fixed limit
Create it from a string or with valueOf
It is immutable, so capture every operation result
add, multiply, pow, and mod cover common math
Use it for factorials, crypto, and any value larger than long

Frequently asked questions

Is the “BigInteger for Huge Numbers” lesson free?

Yes — the full text of “BigInteger for Huge Numbers” is free to read here on the web, and the Java Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Java Academy course, upgrade to CoddyKit PRO.

What will I learn in “BigInteger for Huge Numbers”?

Arbitrary-precision integers. You practise Java Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Java Academy?

No prior experience is required. Java Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “BigInteger for Huge Numbers” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Java Academy lesson?

Yes. Every Java Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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