Concatenating Factorials with Astounding Powers

Find the remainder when 2 2013 ! 2015 ! 2^{2013!*2015!} is divided by 4056195 4056195 . Let this be equal to Z Z . Find sum of digits of Z 2014 ( m o d 1000 ) Z^{2014} \pmod {1000}


The answer is 1.

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2 solutions

Kartik Sharma
Oct 7, 2014

Euler's theorem says a ϕ ( n ) = 1 m o d n {a}^{\phi(n)} = 1 mod n where a & n are co-prime.

Therefore let's find out the totient function of n or 4056195 or 2013 2015 = 3 11 61 5 13 31

ϕ ( p ) = p 1 \phi(p) = p-1 and ϕ ( a b ) = ϕ ( a ) ϕ ( b ) \phi(a*b) = \phi(a)*\phi(b)

hence,

\(\phi(4056195) = 2*10*60*4*12*30

Now, \(2013!*2015!\) has to have all these numbers in it.

Therefore, 2 2013 ! 2015 ! = 1 m o d 4056195 {2}^{2013!*2015!} = 1 mod 4056195

Z = 1, so, z 2014 ( m o d 1000 ) {z}^{2014}(mod 1000) = 1 mod 1000 = 1

Dheeraj Agarwal
Oct 8, 2014

just factorzie 4056195 and use ferrmet theorm

yes 3 * 5 * 11 * 13 * 31 * 61

Mehul Chaturvedi - 6 years, 8 months ago

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