Quote:
if I have a very large number how can I add and multiply these two numbers without using Big integer in Java??
Big integers are done especially for this purpose.
If you don't want to use big integers, you will have to build yourself a set of functions that will mimic big integers.
The main difference is that you are unlikely to be as efficient as big integers.
Calculate the Factorial of an Integer in C#[
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Search for
big intergers to informations about it works. But since about every language have now a big integer library, you will be flooded with such answers. You will have to refine the query to find what you want.