The bitwise right shift is a great method to divide a number by 2 at each position, so division by power of 2, shifting the bit to the right. Note that this operation pads on the left with the most significant bit, that is the sign bit, so everything will be padded by one, but the following example will make everything easier:
zarrelli:~$ x=160 ; echo $((x>>1))
80
zarrelli:~$ x=160 ; echo $((x>>2))
40
zarrelli:~$ x=160 ; echo $((x>>3))
20
zarrelli:~$ x=160 ; echo $((x>>4))
10
So, let's start with 160:
10100000
|
128 |
64 |
32 |
16 |
8 |
4 |
2 |
1 |
|
1 |
0 |
1 |
0 |
0 |
0 |
0 |
0 |
|
128 |
32 |
What we will do now is to shift one position to the right:
1010000
|
128 |
64 |
32 |
16 |
8 |
4 |
2 |
1 |
|
0 |
1 |
0 |
1 |
0 |
0 |
0 |
0 |
|
64 |
1 |
Now we have 80, but again, one position to the left:
|
128 |
64 |
32 |
16 |
8 |
4 |
2 |
1 |
|
0 |
0 |
1 |
0 |
1 |
0 |
0 |
0 |
|
32 |
8 |
Now, as an exercise, calculate by yourself the remaining values.