It based on UK regional settings. If your regional settings are not compatible then, this session will be harder to follow, We have already seen that excel interprets date as a number .

entry into a cell in Excel

Once, You have made an entry into a cell in Excel that entry will be interpreted according to excels internal rules, if it is interpreted as a date. It will attract a date serial number the date serial number is what you will see in that cell. If you strip away the date formatting.

How To Use Serial Numbers 1

How To Use Date & Serial Numbers In Excel

To understand how use serial numbers. It is probably best to look at some For example, in cell a2 type zero one forward slash zero one nine zero this date, the first of January 1900 is the date when excels data serial number kicks off each day that elapses the serial number goes up by one.

How To Use Serial Numbers 2

If I type in o2 forward-slash oh one four slash one nine zero. We can see the serial number has gone up to two. If I type in a more recent date in 2019. We can see that the serial number is approaching 44,000. Having dates set up in excel with this date serial number makes the manipulation addition, subtraction, and all sorts of other operations much easier to perform on dates for excel.To recognize a date has to be entered in a certain way. 

How To Use Serial Numbers 3 (1)
How To Use Serial Numbers 3 (2)

The intuitive ones will automatically be interpreted

How To Use Serial Numbers ? Fortunately, there are a choice of ways and a lot of the intuitive ones will automatically be interpreted as dates, as you can see so far we have entered dates with forwarding slashes and hyphens .We have all sent a date with month letters providing, we have the first three letters that will work we can enter dates without the day.

How To Use Serial Numbers 4 (1)
How To Use Serial Numbers 4 (2)
How To Use Serial Numbers 4 (3)

How To Use Serial Numbers Type Number Without Space

Now type on October 19 with no spaces and we can see that this attracts the date of the 1st of October, one of the rules that excel has when it interprets dates. If you don't give a day, it will default to the first of that month, we can use spaces in some circumstances and they don't always work so for example if I type in a1 October 19 that works.

Use Number With Spaces

If I use numbers with spaces and type in a1 10 2019 then the date isn't interpreted as a date it's just been interpreted as text in terms of months you can type in oct for October, you could type in the whole month either we'll return the date. If I type in the month and year excel recognizes that as a date.

If I type in an equal sign followed by a number a backslash and another number excel will still see a date here because the cell already has a custom date format. if the sale didn't have date format and I typed in the same equals 10 divided by 19.

Then excel would recognize that, as a normal number touch on time in cell e2 if I type in 0.25 enter. We can see that the time 6 am has been returned this time. If I type in 0.5 control enter it's midday if I type in 0.75. It's actually 6 p.m. time effectively works, like a fraction of the serial number of one excel makes an interpretation.

As to which century we're in, if I was to type on October 29 excel recognizes that as the first of October 2029. If I type on October 30 then excel recognizes that as 1930. So, any year 30 or above will be recognized as the last century in the year 29 or below excel will recognize as the current century thank you.