>Can I operate directly to a datetime() with using numeric to characters transformations ?
>
>For example:
>
>store datetime() to my datime
>
>Sum 40 mintures to myDatetime
>
>Sum 2 hours to myDatetime
>
>Moises

The question is not clear.

If you want to add 40 minutes, then use

40*60

If you want to add 2 hours, then use

2*60*60.

The incrementing of datetime value is done in seconds.