How can I multiply and add very long number ?

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My question is, if I have a very large number how can I add and multiply these two numbers without using Big integer in Java??

EX :

23478653794837 * 834723742395729

or
23478653794837 + 834723742395729

Posted 5-Oct-15 9:35am

Member 12034855

Updated 5-Oct-15 18:49pm

Manas_Kumar

v3

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Patrice T · Answer 1 · 2015-10-05T16:55:00

Solution 1

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#[^]

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.

Posted 5-Oct-15 16:55pm

Patrice T

Updated 6-Oct-15 13:22pm

v3

Comments

Matthew Dennis 5-Oct-15 23:12pm

for an example of using BigInteger see my tip http://www.codeproject.com/Tips/270413/Calculate-the-Factorial-of-an-Integer-in-Csharp

Patrice T 6-Oct-15 3:28am

Thank you.
incorporated in solution

[no name] 6-Oct-15 17:18pm

thank you but I'm trying to do so without using BigInteger

[no name] 6-Oct-15 17:18pm

thank you but I'm trying to do so without using BigInteger

Matthew Dennis 6-Oct-15 17:26pm

Then you are probably trying to implement and divide-and-conquer algorithm for your Algorithms and Data Structures course.
When I took it, we had to calculate 72!, which has 100 digits. I had to do it in Pascal.
The trick is to break it into chunks that you can add or multiply, do the operation on the chucks, and then recombine them into a structure that can hold the result, possibly an array.

CPallini 7-Oct-15 5:05am

My 5. Please note the OP asked about Java.

Member 12039237 · Answer 2 · 2015-10-06T22:59:00

Solution 3

one classical way:
- treat your number like string.
- multiply & add like the way you did when you was a child.
sample:
23*45 = (5*3+ 5*10*2) + (4*3+4*10*2)*10

by this way, you can multiply & add all Big integers (like 1123222434324323233535345345345345435345454334543 343294324324302432
*23429492349329433289393895348958934540940958068594695486954864846805486
....
)

Posted 6-Oct-15 22:59pm

Member 12039237

Updated 6-Oct-15 23:00pm

v2

Comments

CPallini 7-Oct-15 5:05am

5.This is an option.

Member 12039237 7-Oct-15 5:13am

In the past (before y2k), I have to add two numbers (one hundred digit numbers).
and I did it.