1. ## Modulo Arithmetic

Hey guys. Could somebody help me please?

i was ill the day the lecture on modulo was on and lecture notes dont make sence to me

a) find a number in Z/7 which gives 1 mod 7 when multiplied by 3

b) use the answer to (a) to solve the equation 3n=4 in Z/7

thank you guys!

Best Regards

2. Originally Posted by boomshine57th
Hey guys. Could somebody help me please?

i was ill the day the lecture on modulo was on and lecture notes dont make sence to me

a) find a number in Z/7 which gives 1 mod 7 when multiplied by 3

b) use the answer to (a) to solve the equation 3n=4 in Z/7

thank you guys!

Best Regards
a. $\displaystyle 5$ b/c $\displaystyle 5 \cdot 3=1 \in Z/7.$
b. similar to part a.

3. Originally Posted by boomshine57th
Hey guys. Could somebody help me please?

i was ill the day the lecture on modulo was on and lecture notes dont make sence to me

a) find a number in Z/7 which gives 1 mod 7 when multiplied by 3
To coin a phrase, "just DO it". What is 3*1 (mod 7)? What is 3*2 (mod 7)? What is 3*3 (mod 7)? What is 3*4 (mod 7)? What is 3*5 (mod 7)? ?What is 3*6 (mod 7)?

b) use the answer to (a) to solve the equation 3n=4 in Z/7
I don't see how the answer to (a) helps to solve that equation but the [b]method does: while you were calculating those, which was congruent to 4 (mod 7)?

thank you guys!

Best Regards