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2012-02-20, 02:42   #3
CRGreathouse

Aug 2006

5,869 Posts

Quote:
 Originally Posted by Raman $2^{20} = 76 (mod 100)$ => is being the identity element over Z/100Z
I'm not sure what you're saying here. 2^20 = 76 is not the identity element in Z/100Z. 2 divides 100, so no positive power of 2 can be the identity.

Quote:
 Originally Posted by Raman $3^{2500} \ne 1 (mod 100000)$ => is Not being the identity element at all
No, the identity is 3^5000 = 1.