https://itpro.tv/course-library/network1/subnetting-example-16/

Subnetting example 4

If I add up 128+64+32+16+8+4+2+1 we get 255

When we borrow a digit from the network we double 256 (256+256) then -(2) Subtract 1 for the subnet IP and 1 for the Broadcast IP

```
1. 192.168.00000000 |.00000000 /24 (254 hosts) 256-(2)=254 (2) being the Subnet IP and the Broadcast IP
2. 192.168.0000000 | 0.00000000 /23 (510 hosts) If we borrow 1 bit from the network side we can double our host. 256+256=512-(2)=510
3. 192.168.000000 | 00.00000000 /22 (1022 hosts) If we borrow another 1 bit from the network side we can double our host again. answer 512+512=1024-(2)=1022
4. 192.168.00000 | 000.00000000 /21 (2046 hosts) If we borrow another 1 bit from the network side we can double our host again. 1024+1024=2048-(2)=2046
```

**If I add up 128+64+32+16+8+4+2+1 we get 255**

*Why do we double 256 and not 255*