The site has $2^{32−20} = 2^{12} = 4096$ addresses.

We need to add 7 more 1s to the site prefix (2x ≥ 100; x = 7).

Prefix = 20

Total Addresses = 4096 prefix needs an additional 29 (512) to allow for at least 100 subnets restricted to 8 addresses

$2^{32−27} = 2^5 = 32$. Each of the 100 organizations has 32 addresses, but only 8 are needed. We add 2 more 1s to the site prefix.

$2^{32−29} = 8$.

Subnet Mask = 120.60.4.0 /29

1st subnet: 120.60.4.0/29 to 120.60.4.7/29

2nd subnet: 120.60.4.8/29 to 120.60.4.15/29

... ... ...

32nd subnet: 120.60.4.248/29 to 120.60.4.255/29

33rd subnet: 120.60.5.0/29 to 120.60.5.7/29

... ... ...

64th subnet: 120.60.5.248/29 to 120.60.5.255/29

... ... ... 99th subnet: 120.60.7.16/29 to 120.60.7.23/29

100th subnet: 120.60.7.24/29 to 120.60.7.31/29

Subnets:

Addresses left after allocation: 4096 – 800 = 3296