001 Subnet-calculator-1-You-wont-have-the-calculator-in-the-exam-so-you-will-need-to-learn-how-to-do-this-
https://configureterminal.com/software/subnetting

001 Subnet-Calculator-2-Subnet-Calculator
http://learnccna.net/ip-subnet-calculator-2/D8A43B6EE6F0CC30DD82E359FBE9743454B8F5098894BB9384B6832A02D2234D49DE839783CA5A55A2F46F4518DD765B/?net_class=A

001 Here-is-a-Solarwinds-FREE-subnet-calculator-
https://goo.gl/5Gpbtp