For me exact age means the exact number of years, the exact number of months and the exact number of days of your life in this planet. Your knowledge in Mathematics will be applied here to compute your exact age. It maybe by applying addition, subtraction, multiplication and division. Before computing your exact age, first you have to familiarize the months of year and days of months. There are twelve months in a year such as (1) January  31 days, (2) February  28 days plus 1, if it is leap year, (3) March  31 days, (4) April 
30 days, (5) May - 31, (6) June  30 days, (7) July  31, (8) August  31 days, (9) September  30 days, (10) October  31 days, (11) November  30 days and (12) December - 31 days. Assuming you want to know your exact age today. Your birth date recorded on your birth certificate is December 23, 1980. Today is December 23, 2010. Your exact age is 30year old today. How did you arrive that answer? Looking at those dates, you immediately subtracted (2010  1980) = 30. This is right because you were born with the same month and day. The proper computation for your exact age based from those dates and by applying subtraction method will be: Present date minus your Birthday dateas shown below  starting subtracting the day then month then year. 2010