Service Availability Math in 9’s

Usually some engineers get confused when it comes the service availability when it comes to number of 9’s.

Uptime            Downtime (Yearly)
99.00000%      3d 15h 39m
99.90000%      8h 45m 56s
99.99000%      52m 35s
99.99900%      5m 15s
99.99990%      31s
99.99999%      3s