The trend of huge number (2)

2016 ! 2017 ! 2018 ! × 2015 ! 2016 ! 2017 ! ? ( m o d 2017 ) \large {2016!}^{{2017!}^{{2018!}}} \times {2015!}^{{2016!}^{{2017!}}} \equiv \, ? \pmod {2017}

Notation : ! ! denotes the factorial notation. For example, 8 ! = 1 × 2 × 3 × × 8 8! = 1\times2\times3\times\cdots\times8 .

Hints :You may find Wilson's theorem useful.

2016 2 2015 1

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1 solution

Tommy Li
Jun 17, 2016

2017 2017 is a prime

( 2017 1 ) ! 1 ( m o d 2017 ) (2017-1)! \equiv -1\pmod {2017}

2016 ! 1 ( m o d 2017 ) 2016! \equiv -1\pmod {2017}

2016 ! 2017 ! ( 1 ) 2017 ! ( m o d 2017 ) {2016!}^{2017!} \equiv (-1)^{2017!}\pmod {2017}

2016 ! 2017 ! ( 1 ) 2 n ( m o d 2017 ) {2016!}^{2017!} \equiv (-1)^{2n}\pmod {2017} , where n n is a positive integer.

2016 ! 2017 ! 1 ( m o d 2017 ) {2016!}^{2017!} \equiv 1\pmod {2017}

2016 ! 2017 ! 2018 ! 1 ( m o d 2017 ) {2016!}^{{2017!}^{2018!}} \equiv 1\pmod {2017}


2016 ! 1 ( m o d 2017 ) 2016! \equiv -1\pmod {2017}

2016 ! 2016 ( m o d 2017 ) 2016! \equiv 2016\pmod {2017}

2016 ! 2016 2016 2016 ( m o d 2017 ) \frac{2016!}{2016} \equiv \frac{2016}{2016}\pmod {2017}

2015 ! 1 ( m o d 2017 ) 2015! \equiv 1\pmod {2017}

2015 ! 2016 ! 2017 ! 1 ( m o d 2017 ) {2015!}^{{2016!}^{{2017!}}}\equiv 1\pmod {2017}


2016 ! 2017 ! 2018 ! × 2015 ! 2016 ! 2017 ! 1 × 1 ( m o d 2017 ) {2016!}^{{2017!}^{{2018!}}} \times {2015!}^{{2016!}^{{2017!}}} \equiv 1 \times 1 \pmod {2017}

2016 ! 2017 ! 2018 ! × 2015 ! 2016 ! 2017 ! 1 ( m o d 2017 ) {2016!}^{{2017!}^{{2018!}}} \times {2015!}^{{2016!}^{{2017!}}} \equiv 1 \pmod {2017}

In general, we have ( ( p 1 ) ! ) m × ( ( p 2 ) ! ) n ( 1 ) m ( m o d p ) ((p-1)!)^m\times ((p-2)!)^n\equiv (-1)^m\pmod{p} for all odd primes p p and non-negative integers m , n m,n . This follows from Wilson's Theorem and it's extension that ( p 2 ) ! 1 ( m o d p ) (p-2)!\equiv 1\pmod{p} for all odd primes p p .

Prasun Biswas - 4 years, 11 months ago

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