'Excel - Convert dates to numbers confusion

I have following error data:

for example instead of value 1.65, date January 65 is writen

enter image description here

When I try to converter it with the Cell formater to a decimaml number I get this

enter image description here

Why I am not geting what I expect?



Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source