00:01
We have given group is u16.
00:03
We have to find a group that is similar to this and a very well known.
00:10
Firstly, write the elements of u16 group.
00:14
U16 is a group under modulus 16 that gives so the elements having are 1, 3, 5, 7, 9, 11, 13 and 15.
00:30
These are the only element less than 16 that gives gcd with 16, 1.
00:37
So now find the nature of these elements.
00:40
If we multiply 3 and 11, we get 11 into 3 that is 33 and 33 modulus 16 gives us remainder 1.
00:57
So that means 3 is the inverse element of 11 and 11 is the inverse element of 3.
01:05
Now for next step this 13 and 5.
01:11
13 into 5 is 65 and 65 modulus 16 give us remainder 1.
01:21
So that means it is also here 5 is the inverse of 13 and 13 is the inverse of 5.
01:27
From next 1 is the unity element or 1 is the identity element.
01:33
It is inverse image of itself.
01:35
So no need to find its inverse image and remaining we can't find it here.
01:40
Now just find the order of the element.
01:42
Order of the element is the number in number a has order n.
01:48
Element a has order n if it gives 1.
01:53
If it gives a identity element after operating n times.
01:58
Now 1 is the also identity which is already identity for no need to find its value.
02:04
So 1 power 1 is 1 so its order will be 1.
02:07
Now find the order of 3.
02:10
If we do the power of 3.
02:13
3 ones are 3 is 3.
02:16
3 power 2 is 9.
02:19
3 power 3 is 27.
02:22
And 3 power 4 is 81.
02:28
If with this taking modulus 16 it does not gives 1 remainder.
02:33
Does not give remainder 1.
02:35
Does not give remainder 1.
02:37
But if from here it divided with 16 it gives remainder 1.
02:41
That mean the element 3 has order 4.
02:45
The inverse element of 3 was 11 that mean 11 also has order 4.
02:51
Now comes to 5.
02:54
5 power 1 is 5.
02:57
5 power 2 is 25.
03:00
5 power 3 is 125.
03:04
And 5 power 4 that is 625.
03:10
If we divide 625 by 16 we get remainder 1.
03:17
So that mean 5 has also order 4.
03:21
And 5 was the inverse image of 13.
03:24
So therefore 13 also has order 4.
03:28
Comes to this point.
03:29
Now we have the element next is 7.
03:32
7 power 1 is 7.
03:35
7 power 2 is 49.
03:38
If we divide 49 with 16 we get remainder 1.
03:43
So 7 power 2 gives remainder 1.
03:46
So that mean 7 has order 2.
03:48
Similarly for 9.
03:50
9 power 2 is 81 that gives remainder 1 when we divided with 16.
03:55
So 9 has also order 2.
03:58
Comes to 15.
04:00
15 power 1 is 15.
04:03
15 power 2 that is 225...