Could we calculate Mod for huge number in GATE Virtual Calculator ?

Question

Normally everyone will depend on calculator to save time . It would be greatful if I could know upto what extend the calculator shows exact answer .

Does anybody knows how to report it to GATE People ? In GATE 20016 this same question asked for 2 marks . And many people dependend on Calculator to save time has suffered a lot !

This aswer is actually 4 . GATE Virtual Calculator was showing an error !

Comments

see Fermat's premality test

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Fermat's little theorem

https://en.wikipedia.org/wiki/Fermat%27s_little_theorem

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this is orignal sol of que.. in exam time we only depends on calculator?? how we think like this @digvijay