Three 9's is .36525 days per year. So if this one is resolved within 8 hours, that's about .999 uptime. (assuming they only have one such outage this year.)
Prescient comment as the Outlook service disruption enters
its second day. (Though to be fair, I hear most everything
is up, just possibly a little slow.) They can still go for
another day and a half and claim they have two 9's of
reliability.