Some numbers in Libre Office Calc displayed incorrectly

Hi,

in my Libre Office Calc a number column e.g. looks like this: the third entry is divided by 1000 and displayed in other format. This happens in some random cells of my columns. Cell formating affects only the correct cells, not the bad ones. Can you help?
Thanks, Heinz

3296
3334
3.34
3343

What’s your LibO locale? What “language” is set for the number formatting of the concerned cells? What Versioin of LibO are you using? Are the concerned numbers direct content or formula results?
Please state explicitly whether or not the “defective cells” withstand a change of the number-format.

(Don’t use the answer tool, but edit your question to append additional information.)
Attaching a little spreadsheet file (.ods) showing the issue for you would help very much.

Cell formating affects only the correct cells, not the bad ones

Which is an indicator that 3.34 is not a number but text.