136.181.0.0/16 (255.255.0.0)
(N = Network, S = Subnet, H = Host)
10001000.10110101.00000000.00000000
NNNNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH
NNNNNNNN.NNNNNNNN.SSSSHHHH.HHHHHHHH
01: 136.181.00000000.00000000/19 (136.181.0.0)
02: 136.181.00010000.00000000/19 (136.181.16.0)
03: 136.181.00100000.00000000/19 (136.181.32.0)
04: 136.181.00110000.00000000/19 (136.181.48.0)
05: 136.181.01000000.00000000/19 (136.181.64.0)
06: 136.181.01010000.00000000/19 (136.181.80.0)
07: 136.181.01100000.00000000/19 (136.181.96.0)
08: 136.181.01110000.00000000/19 (136.181.112.0)
09: 136.181.10000000.00000000/19 (136.181.128.0)
10: 136.181.10010000.00000000/19 (136.181.144.0)
11: 136.181.10100000.00000000/19 (136.181.160.0)
12: 136.181.10110000.00000000/19 (136.181.176.0)
13: 136.181.11000000.00000000/19 (136.181.192.0)
14: 136.181.11010000.00000000/19 (136.181.208.0)
15: 136.181.11100000.00000000/19 (136.181.224.0)
16: 136.181.11110000.00000000/19 (136.181.240.0)
You want 11 subnets, so you need 4 subnet bits creating 16 (2^4) subnets with 4094 (2^12-2) usable host addresses.