To find out how long the system has been running

For Windows:

• go to Command (Windows  + R, type “cmd”)
• type: net statistics server

For Linux/Mac:

• In Terminal, type : uptime
• The result would be like this

  $ uptime [RET]
  3:34pm  up  4:31,  4 users,  load average: 0.01, 0.05, 0.07
  $