Find the remainder!

Level pending

Find the remainder when 2^133 is divided by 133. I'm stuck with this problem please help.

1 128 4 131

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.

1 solution

Let x = 2 133 x = 2^{133} . Note that 133 = 7 19 133 = 7 * 19

x = 2 133 2 133 ( m o d ϕ ( 7 ) ) ( m o d 7 ) x = 2^{133} \equiv 2^{133 \pmod{\phi(7)}} \pmod{7}

x 2 133 ( m o d 6 ) 2 1 2 ( m o d 7 ) \rightarrow x \equiv 2^{133 \pmod{6}} \equiv 2^1 \equiv 2 \pmod{7}

And, x = 2 133 2 133 ( m o d ϕ ( 19 ) ) ( m o d 19 ) x = 2^{133} \equiv 2^{133 \pmod{\phi(19)}} \pmod{19}

x 2 133 ( m o d 18 ) 2 7 128 14 ( m o d 19 ) \rightarrow x \equiv 2^{133 \pmod{18}} \equiv 2^{7} \equiv 128 \equiv 14 \pmod{19}

So we have x 2 ( m o d 7 ) , x 14 ( m o d 19 ) x \equiv 2 \pmod{7} , x \equiv 14 \pmod{19}

We can write x = 7 y + 2 x = 7y + 2

x = 7 y + 2 14 ( m o d 19 ) \rightarrow x= 7y + 2 \equiv 14 \pmod{19}

7 y 12 ( m o d 19 ) 7y \equiv 12 \pmod{19}

77 y 132 ( m o d 19 ) 77y \equiv 132 \pmod{19}

y 18 ( m o d 19 ) y \equiv 18 \pmod{19}

We can write this as y = 19 z + 18 y = 19z + 18

x = 7 y + 2 = 7 ( 19 z + 18 ) + 2 = 133 z + 126 + 2 = 133 z + 128 x = 7y + 2 = 7(19z + 18) + 2 = 133z + 126 + 2 = 133z + 128

x 128 ( m o d 133 ) \rightarrow x \equiv \boxed{128} \pmod{133}

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...