Subnetting in RIPv2

gugalicious

I'm having trouble understanding a routing concept. As an example, I have seven LAN networks (EDIT: Only one is directly connected, R1 contains 2 LANs, R2 contains 2 LANs, and R3 contains 2 LANs, Hub and spoke model), each requiring 150 hosts, that have to be subnetted using the address space 10.1.16.0/21. For simplicity let's exclude WAN link address allocation. My understanding is that every LAN address needs eight host bits, and they would be subnetted as 10.1.16.1/24 , 10.1.17.1/24 , 10.1.18.1/24 etc. But do these addresses fall within the 10.1.16.0/21 domain? Thank you!