00:01
Okay, so in this question we want to pretty much write our addition and multiplication table for the mod 5.
00:06
So i've just written up a table.
00:09
So 0 plus 0 multiply so that's 0 plus 1 is just 1.
00:13
0 plus 2 is 2, 0 plus 3 gives you 3.
00:16
0 plus 4 just gives you 4.
00:20
Now this addition is the same thing for this column, so this would be 0, so this would be 1, so this would be 2, this will be 3, and this will be 4.
00:28
So same thing for this one.
00:29
So we have 1 plus 1 give you 2, 2 mod 5, 2 2 plus 2 give you 3 mod 5 just 3, 1 plus 2 gives you 3 mod 5, 1 plus 4 gives you 4, 1 plus 4 gives you 5, now 5 5 gives you 5 5 5 gives you 0.
00:41
And we'll copy this column here.
00:43
This is 3, 4 and 0.
00:46
Now 2 plus 2 gives you 4, so that's just 4.
00:48
2 plus 3 gives you 5, mod 5 which is 0...