calc, large numbers show as 2E+05 3E+05

edit

I have an existing .ods file that I have been using for years and carrying forward through updates, adding some numbers and data as years go by.

Opening the file which I last saved spring / summer 2018, in one area of my calc file the six digit numbers are displayed as:

2E+05 3E+05 4E+05 etc

Something which I have never seen before.

When I click on any of those, the data entry box shows the correct 6 digit number 123456 234567 345678. When I check the formatting of that line, it has not been changed, it is just plain "number"

It seems to be only with 6 digit numbers. Those with 1 - 5 digits are fine.

Questions: How did this come about, suddenly 8-10 years in? and more importantly How do I fix this?

My current installed version is 5.4.6.2 (downloading 6+ in the background at the moment)

As it is a large spreadsheet the font is Arial 5 to get as much on screen as possible and avoiding ### but that is not what it is showing.

Is this "odd numbering scheme / number notation " a new way of saying whatever I have does not quite fit?

I tried to search google and some forums, did not come up with a solution; other than hints that this may be engineering notation.

Thanks in advance for any insights and solutions.

PS: can't share the file publicly, it is big and contains too much information that would have to be scrubbed out and anonymized.