Remainder again....:-(:-(

Find the remainder when 5 0 5 1 53 \huge50^{51^{53}} is divided by 11 \huge11 .

8 3 5 7 9 2 6 4

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Rama Devi
May 23, 2015

Euler number E(11) = 11(1-1/11) = 10

Now, if D^m is the number whose remainder is to be found out.then D^E gives remainder 1 when divided by N

here, D= 50 m = 51^52

We should express m in terms of E. So 51^53 is to be written in the form of 10k + a. Now unit digit of 51^53 = 1 => 51^53 = 10k + 1.

=> 50^51^53 = 50^(10k + 1) = 50mod11 = 6mod11.

thus, Answer = 6 .

Mas Mus
May 4, 2015

Since gcd ( 50 , 11 ) = 1 \gcd(50, 11)=1 , we can use Euler's Theorem. First, we need to find 53 53 modulo ϕ ( 10 ) = 4 \phi(10)=4 , second, we need to find 51 53 {51}^{53} modulo ϕ ( 11 ) = 10 \phi(11)=10 , and the last we need to find 50 51 53 \large{{50}^{{51}^{53}}} modulo 11 11 .

53 1 ( m o d 4 ) 51 53 51 1 1 ( m o d 10 ) 50 51 53 50 1 6 ( m o d 11 ) 53\equiv1\pmod{4}\\{51}^{53}\equiv{51}^{1}\equiv1\pmod{10}\\\large{{50}^{{51}^{53}}}\equiv{50}^{1}\equiv6\pmod{11}

In last three lines you have just plugged in the values one after the other , but modulo is also changing from m o d 4 mod 4 to m o d 10 mod 10 and then to m o d 10 mod 10 .We don' t need to care of them ??Just plug in the values ? Please explain.

Chirayu Bhardwaj - 5 years, 2 months ago

Log in to reply

For more explanation please check Euler's Theorem . also, you can chek this problem and this , or this

Mas Mus - 5 years, 2 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...