What namespace is needed to use BigInteger in Windows Phone silvelight application?

Question

I want to use BigInteger in my Windows Phone silvelight application. What namespace is needed to use it? Why it is not supporting to using System.Numerics; For BigInteger, my code is here:

BigInteger n = new BigInteger("19579160939939334264971282204525611731944172893619019759209712156289528980860378672033164235760825723282900348193871051950190013953658941960463089031452404364269503721476236241284015792700835264262839734314564696723261501877759107784604657504350348081273959965406686529089170062268136253938904906635532824296510859016002105655690559115059267476786307037941751235763572931501055146976797606538425089134251611194500570922973015579287289778637105402129208324300035518642730384616767241853993887666288072512402523498267733725021939287517009966986976768028023180137546958580922532786773172365428677544232641888174470601681", 10);

Answer 1

C# PCL library for computations with big numbers such as Int128 and Int256. https://github.com/Taggersoft/BigMath

Answer 2

You can try using the Int128 library from CodePlex.