If you blinked, you missed it.
Mathematicians were celebrating a rare numerical phenomenon today when the time and date read 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
The event, known as Sequential Day, occurred at 12.34pm and 56.7 seconds today, while the date completed the pattern with 8.9.10.
The phenomenon is so rare that the last ‘pure’ sequence fell at 01.23.45am on 6.7.89 and the next will take place at 00.12.3am on 4.5.67 – in 2067.
Maths teacher Chris Hawkins, of specialist math school Thomas Deacon Academy in Peterborough, Cambs., spotted the Sequential Day.
He said: ”I do like to spot strange dates like this. Next month it will be 10.10.10 and I have seen things like this before.
”Obviously the Americans will have marked it last month because of the way they swap the day and month around when writing the date.
”Unlike other dates there is no formula to work out when the next Sequential Day will happen.
”Dates like 10.10.10 and 11.11.11 happen every 13 months and one day, but I can’t think of a way to find a formula for this.”
Other notable mathematical dates include March 14, which is celebrated by Americans as it reads 3.14, representing the first three digits of Pi.
The date is also the birthday of mathematician Albert Einstein.
Mathematicians also mark square root days, which occur when the value of the month and year are the same number that make the last two digits of the year when multiplied together.
The last occurrence of this was on 3.3.09 and the next will be on 4.4.16.
Palindromic days are where the time and date written together read the same forwards and backwards.
The first such occurrence this millennium was when the time read 00.02.11 on 1.1.2000, followed by 00.02.10 on 11.01.2000.