Your organization has been assigned a network address of 213.83.0.0. How can I subnet this network?

Question

Computer networks

Your organization has been assigned a network address of 213.83.0.0 There are currently four subnets on your network. The number of subnets will double during the year. Each subnet must support up to 10 hosts. Determine what the subnet mask must be to support this configuration. Specify the addresses of the last five subnets and hosts, as well as the broadcast addresses for hosts on those subnets and all subnets together.

Address of subnet Mask address Boadcast address of the first host address of Last Host
213.83.0.16 /28 213.83.0.31 213.83.0.17 213.83.0.30
213.83.83.32 /28 213.83.47 213.83.0.33 213.83.0.46
213.83.0.48 /28 213.83.0.63 213.8 213.83.0.62
213.83.0.64 /28 213.83.0.79 213.83.0.65 213.83.0.78
213.83.0.80 /28 213.83.0.95 213.83.0.81 213.83.0.94
213.83.83.0.96 /28 213.83.0.111111113.83.83.0.97 213.83.0.110
213.83.0.112 /28 213.83.0.113 213.83.83.0.126 21.26
21 213.83.0.129 213.83.0.142
I did like this, but it confuses me that I use the /28 mask when my address in binary form takes only 16 bits. Please tell me did I do it right?