In need to find the age in days - months - years in OpenOffice.

There is DATEDIF() in Microsoft Excel. You can use it to find the difference in days/months/years between two dates.

Age Calculation 
    You can calculate a persons age based on their birthday and todays date.
    The calculation uses the DATEDIF() function.        
    The DATEDIF() is not documented in Excel 5, 7 or 97, but it is in 2000. 
    (Makes you wonder what else Microsoft forgot to tell us!)   
    Birth date :    01-Jan-60       
    Years lived :   52   =DATEDIF(C8,TODAY(),"y")   
    and the months :    4    =DATEDIF(C8,TODAY(),"ym")
    and the days :  30   =DATEDIF(C8,TODAY(),"md")

One can calculate by below formula, but it is cumbersome to calculate months.

Another way to calculate age         
This method gives you an age which may potentially have decimal places representing the months.
If the age is 20.5, the .5 represents 6 months.             
Birth date :    01-Jan-60
Age is :    52.41    =(TODAY()-C23)/365.25