Here is a method that simplifies the process of subnetting. Hopefully it will help you understand what's really happening when networks are divided up and why subnet masks are important.
For some background information on binary counting and conversion, check out these videos:
How to Count in Binary: https://youtu.be/pDkeQYcefn8
Converting an IP Address to Binary—it’s EASY: https://youtu.be/LCgXbEM1VFI
