how to do number 5 please explain and write properly too tha

how to do number 5? please explain and write properly too. thank you.

1. Write the addition and multiplication tables for Z2. 2. Write the addition and multiplication tables for Zs. 3. Write the addition and multiplication tables for Zs. 4. Write the addition and multiplication tables for Z6 ) Suppose la llbjeZgand la].[b]=[0].ils it necessarily true that eitherla-E01V or [b] = [O]? ) rale aand lalibl =[0],/Is it necessarily true that either[a]=[0],

Solution

5. Yes it is necessary that either [a]=0 or [b]=0.

Because multiplication is zero only if one of the number is zero.